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NFG Forums => Console Mods => Topic started by: RobIvy64 on September 20, 2006, 09:42:37 PM

Title: Overclocking a PS2
Post by: RobIvy64 on September 20, 2006, 09:42:37 PM
Hello! Here is an article I wrote a while back about my experience overclocking the PS2. I get TONS of questions from people asking me to overclock the PS2. Enjoy!

___________________________________________________________________

If you own a Playstation 2, i'm *positive* you have experienced extreme amounts of slowdown at one point or another. Well being the overclocking type that I am, I had to take a crack at this.

I had a spare slimline PS2 that was donated for this purpose, so it was time to get started.

Examining the board, I noticed several crystals (about 8 or 9) on the motherboard providing different clock signals for different functions, but one stood out to me that was right next to the CPU: ~18 MHz. This oscillator is not labelled and the speed was determined by probing the signal with an oscilloscope.

The PS2's CPU runs at 294 MHz, with the GPU operating at exactly half this speed. My fear was that the GPU and CPU would share the same clock signal, but I had to test this to confirm it.

18 x 16 = 294. This was too much of a coincidence for me to pass up, it was time to heat up the soldering iron and pull out a 21 MHz crystal for installation.

After desoldering the original 18 MHz crystal and installing a 21 MHz crystal I reassembled the PS2 and turned it on. My fears were confirmed; the GPU and CPU were both running overclocked; with the CPU running at
343 MHz and the GPU running at 171 MHz. Overclocking the GPU causes the screen to roll, since it it outputting a fequency greater than 60Hz which most TVs cant handle.

Turns out the PS2 is impossible to overclock without causing problems with most standard TVs. The GPU takes the 18 MHz signal, multiplies it by 8 internally, and outputs the signal to the CPU. The CPU takes the GPUs internal clock speed and multiplies it by 2 internally, resulting in a 294 MHz clock speed. It wasn't successful, but I thought some of you might be curious. Cheers!

-Rob
Title: Overclocking a PS2
Post by: Ishan on September 24, 2006, 06:49:05 PM
Ever tried to intercept the signal BETWEEN the gpu and the cpu? It might be a good solution. Never looked @ the PS2 internal myself but maybe it's a good idea to check that :)
Title: Overclocking a PS2
Post by: RobIvy64 on September 25, 2006, 12:35:58 PM
No dice unfortunately. It is some sort of bus clock...the PS2's hardware is so screwed up.
Title: Overclocking a PS2
Post by: sebi1000 on September 25, 2006, 03:54:33 PM
If the PS2 would share the same clock signal for GPU and CPU you can try to use a second clockgenerator for the CPU or GPU, but you have to cut the connection between the old Masterclock.
You can also change the 18MHZ crystal with a smaller one, so you can test the function of this crystal. If the PS2 works with a smaller crystal you can try bigger crystals then 18MHZ, but only in small steps like 18,2MHZ , 18,5MHZ ,  18,7MHZ ...
I tried this method at the N64 but a second clockgenerator doesn�t work.
Godd luck!
Title: Overclocking a PS2
Post by: RobIvy64 on September 26, 2006, 04:34:02 AM
QuoteIf the PS2 would share the same clock signal for GPU and CPU you can try to use a second clockgenerator for the CPU or GPU, but you have to cut the connection between the old Masterclock.

Easier said than done. See above post.

QuoteYou can also change the 18MHZ crystal with a smaller one, so you can test the function of this crystal. If the PS2 works with a smaller crystal you can try bigger crystals then 18MHZ, but only in small steps like 18,2MHZ , 18,5MHZ , 18,7MHZ ...

Done. Same results. No matter what you adjust this to, the CPU and GPU's clocks are going to rise, respectively. If you plug in a lower-frequency oscillator, then the CPU and GPU's clocks will decrease, etc.

At 21 MHz (343 MHz  CPU) the PS2 still booted to a rolling picture. The CPU and GPUs quickly warmed up to a higher tempurature than normal.
Title: Overclocking a PS2
Post by: Guest on December 20, 2006, 11:22:50 AM
any more progress on this???/
im very keen
Title: Overclocking a PS2
Post by: RobIvy64 on December 20, 2006, 05:52:45 PM
Nope :(. I've abandoned the project really.

The information I know from my tests are in this thread if anyone else wants to step up and take a stab at it.
Title: Overclocking a PS2
Post by: blackevilweredragon on December 20, 2006, 05:53:55 PM
i might be getting a slim PS2 for christmas..  if you don't mind, i'll take a shot at it..  but, i don't know weather to do it in warranty, or out of warranty..  (is there a sticker on it?)
Title: Overclocking a PS2
Post by: RobIvy64 on December 20, 2006, 05:56:04 PM
Quotei might be getting a slim PS2 for christmas..  if you don't mind, i'll take a shot at it..  but, i don't know weather to do it in warranty, or out of warranty..  (is there a sticker on it?)
There is a sticker on it. Don't get a new one since the GPU and CPU are housed in a custom IC named EE+GS.

You want one with the EE chip (Emotion Engine) seperate from the GS (graphics chip). Early slim PS2s had these, but the newest ones from ~late '05 and up have the EE+GS.
Title: Overclocking a PS2
Post by: blackevilweredragon on December 20, 2006, 05:59:19 PM
hmm, well i need the newer slim PS2 for personal use (the early one had lasers literally melting the lens from being too hot, i hear the newer ones finally fix this)

i'll see if i can pick up a used PS2 (old one, original model perhaps), to try the mod...
Title: Overclocking a PS2
Post by: RobIvy64 on December 20, 2006, 11:56:06 PM
You'll need to probe the board and find a way to intercept the clock signal after it leaves the GPU and before it hits the CPU. That is, if it is interceptable.

Also, keep in mind that there are 38242089023 PS2 board revisions, so the early ones might be entirely different. I wouldn't put it past Sony.
Title: Overclocking a PS2
Post by: GZeus on December 22, 2006, 01:37:54 AM
I'm sure it can be intercepted, and if you find a crystal that's greater than 8x the main one, you can begin overclocking.
Title: Overclocking a PS2
Post by: RobIvy64 on December 22, 2006, 04:25:22 AM
QuoteI'm sure it can be intercepted, and if you find a crystal that's greater than 8x the main one, you can begin overclocking.
Not if the trace is located on an inner layer of the board.
Title: Overclocking a PS2
Post by: blackevilweredragon on December 22, 2006, 04:32:20 AM
exactly..  and being this isn't like older consoles, im sure it's in the inner layer part of the board..
Title: Overclocking a PS2
Post by: GZeus on December 22, 2006, 08:19:33 AM
Not able to lift the pin?
Title: Overclocking a PS2
Post by: blackevilweredragon on December 22, 2006, 08:51:28 AM
QuoteNot able to lift the pin?
not if the pins are like, DIRECTLY under the chip?
Title: Overclocking a PS2
Post by: RobIvy64 on December 22, 2006, 09:16:36 AM
You would have to use an SMD rework station to remove the chips (which are BGA mounted).
Title: Overclocking a PS2
Post by: blackevilweredragon on December 22, 2006, 09:18:14 AM
yea, and that's something i don't have..  I seriously WISH i had it, but i don't...

i'd have to figure out which trace is a clock..  that won't be easy, especially if you can't even access the pins on the chips...  you'd need schematics to pull this one off easily, and as Rob even said, there's like, MANY different revisions of the board..
Title: Overclocking a PS2
Post by: GZeus on December 22, 2006, 09:48:54 AM
Quote
QuoteNot able to lift the pin?
not if the pins are like, DIRECTLY under the chip?
How is that a question?
I've never opened a PS2.
It does make sense that something like that would need piles of mins, though.
Title: Overclocking a PS2
Post by: anonymous guy on January 22, 2007, 12:49:35 PM
could it be possible on a PAL ps2? many PAL TVs accept 50 as well as 60 hz signals... or do pal ps2's output 60 hz already?
Title: Overclocking a PS2
Post by: RobIvy64 on January 22, 2007, 05:27:09 PM
Quotecould it be possible on a PAL ps2? many PAL TVs accept 50 as well as 60 hz signals... or do pal ps2's output 60 hz already?
You wouldn't be able to overclock it by much for it to reach 60 Hz; possibly 1-5 MHz at most.

Hardly not worth the trouble for a performance gain you're likely not going to notice.
Title: Overclocking a PS2
Post by: Guest on January 23, 2007, 12:27:44 PM
Either way the PS2's CPU is halfway decent (not what Sony blew it up to be, but decent) but its GPU is sort of lacking in a lot of areas. Unless 3D transformation math is being done on the CPU I doubt it'll help performance much to overclock it.
Title: Overclocking a PS2
Post by: Epicenter on January 24, 2007, 12:43:38 AM
Not again! damn you, cookies!
Title: Re: Overclocking a PS2
Post by: Lechkovitz on April 06, 2008, 07:36:18 PM
Quote from: RobIvy64 on September 20, 2006, 09:42:37 PM
Hello! Here is an article I wrote a while back about my experience overclocking the PS2. I get TONS of questions from people asking me to overclock the PS2. Enjoy!

___________________________________________________________________

If you own a Playstation 2, i'm *positive* you have experienced extreme amounts of slowdown at one point or another. Well being the overclocking type that I am, I had to take a crack at this.

I had a spare slimline PS2 that was donated for this purpose, so it was time to get started.

Examining the board, I noticed several crystals (about 8 or 9) on the motherboard providing different clock signals for different functions, but one stood out to me that was right next to the CPU: ~18 MHz. This oscillator is not labelled and the speed was determined by probing the signal with an oscilloscope.

The PS2's CPU runs at 294 MHz, with the GPU operating at exactly half this speed. My fear was that the GPU and CPU would share the same clock signal, but I had to test this to confirm it.

18 x 16 = 294. This was too much of a coincidence for me to pass up, it was time to heat up the soldering iron and pull out a 21 MHz crystal for installation.

After desoldering the original 18 MHz crystal and installing a 21 MHz crystal I reassembled the PS2 and turned it on. My fears were confirmed; the GPU and CPU were both running overclocked; with the CPU running at
343 MHz and the GPU running at 171 MHz. Overclocking the GPU causes the screen to roll, since it it outputting a fequency greater than 60Hz which most TVs cant handle.

Turns out the PS2 is impossible to overclock without causing problems with most standard TVs. The GPU takes the 18 MHz signal, multiplies it by 8 internally, and outputs the signal to the CPU. The CPU takes the GPUs internal clock speed and multiplies it by 2 internally, resulting in a 294 MHz clock speed. It wasn't successful, but I thought some of you might be curious. Cheers!

-Rob

I have a theory.
I always wanted to play ps2 games on PC monitors. I do actually, with the VGA cable, but as you may figure, I can only paly games that support progressive scan.
But. CRT PC monitors actually DO support interlaced scan. I know, I tried it myself. The problem is that the TV standards are not enough kHz signal for a PC monitor.
Now then. What if we multiply the ps2's clock speed exactly with 2, (and put some very powerful cooling on the chips) ? We would get exatly double of the refresh rate of the ps2. That would mean that a PC monitor would be able to display all the ps2 games. Of course you will never be able to play on a Tv set though.
Well, how does it sound ?
Title: Re: Overclocking a PS2
Post by: Chizzles on April 06, 2008, 10:48:37 PM
It sounds ridiculous - yay for VGA, boo for most games running 2x faster than normal, do what everyone else does and buy a high grade line doubler or deinterlacer.
Title: Re: Overclocking a PS2
Post by: NFG on April 06, 2008, 11:14:06 PM
Would not overclocking the PS2 also affect the sound, controller polling and all other aspects of the system?
Title: Re: Overclocking a PS2
Post by: l_oliveira on April 06, 2008, 11:38:08 PM
We have differential clocks generated by a PLL controller on the PS2. The same chip generates synchronous clock for the Emotion Engine and RDRAM chips. The GS uses 54mhz clock. On older PS2s the clock for GS comes from a 4 pin oscilator box.

Clocks for sound come from the IOP (It has a 16mhz clock which is multiplied internally to generate 33, 37 and 66MHz internally. A second 24mhz crystal is connected to it for the iLINK hardware on systems that have it enabled. Clock for sound and IOP I/O is generated from the 16mhz IOP clock and is 33mhz.

The Mechanics controller on newer units (units with IR built in) has it's own clock generator, too and the calendar chip built in, having them two clocks connected to it.

The possibility of overclocking the PS2 is dim not due to hardware design but mostly due to how it's software works. It's hardware is built with several asynchronous subsystems and overclocking would break the sync.

Attached is a copy of the section of schematics which covers the PLL IC which genetates clock for RDRAM and Emotion Engine chips.
Title: Re: Overclocking a PS2
Post by: Lechkovitz on April 07, 2008, 01:35:32 AM
Quote from: Chizzles on April 06, 2008, 10:48:37 PM
It sounds ridiculous - yay for VGA, boo for most games running 2x faster than normal, do what everyone else does and buy a high grade line doubler or deinterlacer.

That doesn't mean that games will run 2x faster! They will just have a higher refresh rate.

BTW I had an XRGB2 once wich is said to be the best quality upscan converter, and guess what. I think it sucked.
Title: Re: Overclocking a PS2
Post by: Chizzles on April 07, 2008, 05:05:47 AM
Some games rely on the refresh rate for timing - if you double the refresh rate on those games it will double the speed.

And yes, the XRGB2 does suck at line doubling interlaced video, that's why you buy an adaptive deinterlacer that only deinterlaces the area of the image that suffer from "toothing".  :P
Title: Re: Overclocking a PS2
Post by: Lechkovitz on April 07, 2008, 06:55:52 PM
Quote from: Chizzles on April 07, 2008, 05:05:47 AM
Some games rely on the refresh rate for timing - if you double the refresh rate on those games it will double the speed.

And yes, the XRGB2 does suck at line doubling interlaced video, that's why you buy an adaptive deinterlacer that only deinterlaces the area of the image that suffer from "toothing".  :P

Hmm. that sound interesting. Can you recommend one ?
Title: Re: Overclocking a PS2
Post by: l_oliveira on April 08, 2008, 04:51:20 AM
Quote from: Chizzles on April 07, 2008, 05:05:47 AM
Some games rely on the refresh rate for timing - if you double the refresh rate on those games it will double the speed.

And yes, the XRGB2 does suck at line doubling interlaced video, that's why you buy an adaptive deinterlacer that only deinterlaces the area of the image that suffer from "toothing".  :P

In fact most games do. Everything (console) up to the Saturn used the video interrupts for timming.
Some companies did fix their games (nintendo) so it would not look too bad. An good test would be pick a SNES game such as PAL Super Mario Kart and try it on a NTSC SNES.  It would play much faster.
Other companies like, for example SEGA would not fix their games (Sonic on the Mega Drive) for playing on the same speed as it does in NTSC, resulting on slower gameplay and musics... (LOL)

Well ... on PC, games use the system timer for sync so it can run on any refresh rate.

I'm not a programmer but I believe in the PS2 one can use either timers or just hook the game into the raster on the Graphics Synthesizer frame buffer.

Anyway, the last is not likely to be the method used on games that do support "Progressive Scan"

Datasheets for the clock synthesizer chip would help greatly on hacking this. I can at least provide the chip pinouts if anyone is really willing to attempt performing this mod.
Title: Re: Overclocking a PS2
Post by: Endymion on April 08, 2008, 06:24:44 AM
Quote from: Lechkovitz on April 06, 2008, 07:36:18 PM
I always wanted to play ps2 games on PC monitors. I do actually, with the VGA cable, but as you may figure, I can only paly games that support progressive scan.

Solve this problem, just use XPloder HDTV Player.
Title: Re: Overclocking a PS2
Post by: l_oliveira on April 08, 2008, 01:32:35 PM
Easy way (I said easy, not cheap) to play PS2 games:

What's needed:

Original PS2 games

Playstation 3 console (Needs to be eithar 20GB or 60GB of either USA or JPN. PAL work too but has no EE chip) matching the region of the Ps2 games

PS2 linux VGA cable or hack a suitable equivalent (I use a normal PS2 component cable and an adapter built by me with a mini DB15 and the 3 RCAs for connecting the component cable) Hacking the cable is not the best idea if you plan to keep it for TV connections.

Monitor which supports Sync On Green (SoG)

By setting the PS3 to run on 480P on RGB mode one can run ANY PS2 game supported by the PS3 in a VGA monitor that supports Sync On Green.

Sorry to change the topic but this kind of setup isn't documented anywhere I know of. I just wanted to share this.
I use it to play Final Fantasy XI on a 20 GB US PS3.
Title: Re: Overclocking a PS2
Post by: Lechkovitz on April 09, 2008, 12:53:51 AM
Quote from: Endymion on April 08, 2008, 06:24:44 AM
Quote from: Lechkovitz on April 06, 2008, 07:36:18 PM
I always wanted to play ps2 games on PC monitors. I do actually, with the VGA cable, but as you may figure, I can only paly games that support progressive scan.

Solve this problem, just use XPloder HDTV Player.

I do. But it doesn't work with too many games.
Title: Re: Overclocking a PS2
Post by: Lechkovitz on April 09, 2008, 12:59:48 AM
Quote from: l_oliveira on April 08, 2008, 01:32:35 PM
Easy way (I said easy, not cheap) to play PS2 games:

What's needed:

Original PS2 games

Playstation 3 console (Needs to be eithar 20GB or 60GB of either USA or JPN. PAL work too but has no EE chip) matching the region of the Ps2 games

PS2 linux VGA cable or hack a suitable equivalent (I use a normal PS2 component cable and an adapter built by me with a mini DB15 and the 3 RCAs for connecting the component cable) Hacking the cable is not the best idea if you plan to keep it for TV connections.

Monitor which supports Sync On Green (SoG)

By setting the PS3 to run on 480P on RGB mode one can run ANY PS2 game supported by the PS3 in a VGA monitor that supports Sync On Green.

Sorry to change the topic but this kind of setup isn't documented anywhere I know of. I just wanted to share this.
I use it to play Final Fantasy XI on a 20 GB US PS3.

I've heard (and seen some samples on Youtube) that ps2 games don't look too good on ps3 's. In fact they look messed up big time
Title: Re: Overclocking a PS2
Post by: l_oliveira on April 09, 2008, 03:35:29 PM
The emulator has been updated a few times since the release of the console. It's pretty decent now (considering your PS3 is one of the ones with the PS2 CPU built in)
Indeed t was crappier in the past, even introducing graphic bugs on the games in some cases. But they're improving it.

It's not perfect though, I agree.
Title: Re: Overclocking a PS2: Success
Post by: grokr989 on April 30, 2008, 10:23:25 AM
I don't usually frequent forums but I was wondering if I could overclock my PS2 also a few months ago. I am happy to report that using the information in this forum and a service manual for the PS2 I found online, I am succesfully able to overclock my PS2. ;D At first I was discouraged from the results that have been posted. I have an early large SCPH-30001, which is perhaps why my results are different. Anyhow, I changed X101 to a 22.1184MHZ crystal. The exact part number is CS1022.1184MABJ-UT, whihch is manufactured by Citizen. I bought it from Newark Electronics online. The part is surface mount so it is a good replacement for the part on the board. I don't experience any screen rolling effects as others have posted.  8) I tested the overclocking with Odin Sphere which has very noticeable slowdown during parts of the game normally. With my overclocked PS2, the game runs with no more slowdown! ;D However, the sound also plays much faster. All the characters voices are sped up and higher pitched. It's funny to hear King Odin talking like a boy  :D Also, the sound gets out of sync with the onscreen dialog the longer the movie sequence. Aside from that, I am still happy with the results since it allowed me to enjoy parts of the game, especially some boss fights that were annoying becasue of the slowdown before.

Title: Re: Overclocking a PS2
Post by: Lechkovitz on August 29, 2008, 06:35:23 AM
Could you make kinda like a tutorial please ? with pics of that service manual ?
I might try to overclock myslef
Title: Re: Overclocking a PS2: Success
Post by: Lechkovitz on May 21, 2009, 05:33:53 AM
Quote from: grokr989 on April 30, 2008, 10:23:25 AM
I don't usually frequent forums but I was wondering if I could overclock my PS2 also a few months ago. I am happy to report that using the information in this forum and a service manual for the PS2 I found online, I am succesfully able to overclock my PS2. ;D At first I was discouraged from the results that have been posted. I have an early large SCPH-30001, which is perhaps why my results are different. Anyhow, I changed X101 to a 22.1184MHZ crystal. The exact part number is CS1022.1184MABJ-UT, whihch is manufactured by Citizen. I bought it from Newark Electronics online. The part is surface mount so it is a good replacement for the part on the board. I don't experience any screen rolling effects as others have posted.  8) I tested the overclocking with Odin Sphere which has very noticeable slowdown during parts of the game normally. With my overclocked PS2, the game runs with no more slowdown! ;D However, the sound also plays much faster. All the characters voices are sped up and higher pitched. It's funny to hear King Odin talking like a boy  :D Also, the sound gets out of sync with the onscreen dialog the longer the movie sequence. Aside from that, I am still happy with the results since it allowed me to enjoy parts of the game, especially some boss fights that were annoying becasue of the slowdown before.



After some research I have found the same chip on my scph-5000 model motherboard (GH-026)  named X-102, it was pretty much the same as x101 on your model. I have also ordred the same crystal you mentioned. Sadly my experience was a complete failiure :( I guess its because of the different mainboards. Oh wel...
Title: Re: Overclocking a PS2
Post by: grokr989 on September 27, 2009, 04:49:27 AM
Lechkovitz,
I didn't have time to make a tutorial but I just found out I'm going to get laid off in November so I'll probably have more time to work on that. I'll look to see if I can find why it does not work on your version.  These days I just use an emulator so slowdown with games like Odin Sphere isn't a problem anymore as long as you have a decent machine to run the emulator.



Title: Re: Overclocking a PS2
Post by: grokr989 on October 04, 2009, 03:54:50 AM
Lechkovitz,
I checked and in your model X102 drives IC106(The clock generator for both the both the EE(through IC101) and the GS)  so simply replacing X102 with a higher frequency part won't work. It works in my model because X101 drives only IC101(The clock geerator IC for the  EE).  The GS uses a separate crystal(X202).
Title: Re: Overclocking a PS2
Post by: panzeroceania on October 09, 2009, 08:31:23 AM
Quote from: Lechkovitz on April 07, 2008, 06:55:52 PM
Quote from: Chizzles on April 07, 2008, 05:05:47 AM
Some games rely on the refresh rate for timing - if you double the refresh rate on those games it will double the speed.

And yes, the XRGB2 does suck at line doubling interlaced video, that's why you buy an adaptive deinterlacer that only deinterlaces the area of the image that suffer from "toothing".  :P

Hmm. that sound interesting. Can you recommend one ?

I also would like to know good alternatives, even if they are expensive.
Title: Re: Overclocking a PS2
Post by: RobIvy64 on November 11, 2009, 10:17:54 AM
:golf clap:

Good to hear you accomplished it! I never tried this with a fat PS2. Sadly my soldering iron has long been retired for such awesome tomfoolery.  8)
Title: Re: Overclocking a PS2
Post by: jdtheretro on December 18, 2009, 04:29:25 AM
Yea, if you isolated the clock signal, and since the cpu bus multiplier is 2x, if you want it at 343, then have the clock coming from a 171.5 crystal osc.
Title: Re: Overclocking a PS2
Post by: RobIvy64 on January 14, 2014, 01:52:59 PM
Buuuuuuuuuuuuuuuuuuump!

Reading grokr989 information, I realized that I had the exact same version of PS2 sitting in my closet!

I cracked it open and got to work. The stock crystal oscillator is 18 MHz.

First, I tried 27 MHz (27 x 16 = 432 MHz..... LOL). Nothing. Green light, followed by red.

Next, 24 MHz (384 MHz). Powers on, but nothing. Blank screen.

Unfortunately, I don't currently have an oscillator between 18 and 24 MHz, so I decided to UNDERCLOCK in the meantime!

12 MHz (192 MHz CPU).

See results below:
https://www.youtube.com/watch?v=JBhYElftOSg (https://www.youtube.com/watch?v=JBhYElftOSg)

Title: Re: Overclocking a PS2
Post by: RobIvy64 on January 14, 2014, 01:54:36 PM
The audio pitch changes because I suspect the sound CPU (PS1 CPU) shares the same clock speed (x2).

If I can isolate that clock input, set the sound CPU input back to 18 MHz, this will resolve the sound pitch changes.
Title: Re: Overclocking a PS2
Post by: RobIvy64 on January 15, 2014, 08:56:12 AM
I cut the clock to the R3000A, and I still had sound but no CD/DVD drive. Apparently, the PS1 CPU controls the DVD-ROM.

I'll have to probe around the other two ICs and find the clock input.
Title: Re: Overclocking a PS2
Post by: maxdub432 on April 08, 2014, 07:27:32 AM
UPDATE:
Now that summer's over I finally had some more time to throw at this project. I grabbed a fresh PS2 (30001R, mainboard's more like a 39k than a 31k) and tested out my theory about MSCLK needing to be 36.864 rather than 36. System still wouldn't boot with my 36.864MHz oscillator signal connected to the IOP. Switching from the EE signal to my signal after bootup caused an unrecoverable freeze.

Probed the signal from the IOP -> SPU2, also 36.864. Substituting my signal here also failed to boot. Switching from the IOP signal to my signal after bootup caused sound to glitch or drop out. Trying to load any programs led to a soft hang until I switched back to the stock signal. Switching back resulted in normal sound resuming maybe 20% of the time. Unless someone else bumps this topic with new ideas I'm giving up on fixing the audio desync.

I was able to reproduce my overclock on this PS2, so I know firsthand that 30001, 30001R, and 39001 can all be overclocked; I would assume that this applies to all fat models.

Overclocking results in:
noticeable framerate improvement in Odin Sphere (only game I've tested)
audio/video desync, irritating in cutscenes
loss of network & internal HDD capability
usb still works, so you can still load games with OPL

Quote from: UPDATE 2
I originally assumed that networking still worked because my oc'd ps2 grabbed an IP from my router. Actually trying to load games with OPL over SMB/ETH from a known working server, however, always times out

Because of the audio desync, I think the best application of the overclock is to install a switch between the stock and overclocked crystals and only use it for games that you know have a lot of lag. This comes with two additional caveats: one, put the switch as close as you can to X101/X102, because if your wires are too long bootup is unreliable; two: you can't switch the OC on in the middle of a game like you can on the PS1, here it causes a hard freeze. I'm out, hope this helps at least one person out there looking for the info

Quote from: Old Post (Abridged)
I also used grokr's success as a jumping-off point to overclock a PS2 last fall, but rather than sourcing a 30001 I successfully OC'd a 39001. I upgraded the unified CPU/GPU clock crystal (X102), then interrupted the signal from the unified clock generator (IC106) to the GPU at resistor R159 and substituted my own non-OC'd signal from a 54MHz oscillator.

I successfully booted with a ~24MHz X102 but thought it was too fast and eventually settled on ~21MHz. I was bothered not only by the audio desync but also by the inability to use an internal hard drive. I tried to correct both problems at once by interrupting the signal from the CPU to the IOP/IC303 (which is, IIRC, the PS1 R3000A) and substituting my own.

I found that the PS2 wouldn't boot at all with the CPU -> IOP signal missing, presumably because the IOP is needed to pull the BOOTROM into memory, but would continue to run at the OSD if the signal was cut after bootup. The PS2 failed to boot at all when I substituted my own 36MHz signal to the IOP even when using the stock ~18MHz X102.

My multimeter indicated the stock CPU -> IOP signal is not actually 36MHz, but 36.864MHz, exactly twice the value of X102, which is something I could tackle if I could source the proper oscillator, but for now I haven't had the time