My jaw dropped on the floor when after installing PS CS4 Trial I read that there is no GPU functions support for XP x64! I had huge problems with Vista so I go back to Xp x64 just to now that I won’t be able to speed things up with new PS 4 ! THIS SUXS BADLY!!!
:( tried Photoshop 4 no GPU support for XP 64Bits !!!
you’re better off without it…
when I turn on OGL acceleration, I feel like i’m painting on an ol’ Pentium III…
and I have a 9600GT…
still needs some work…
Neither can I and I’m on a 32bit OS, my graphic card Geforce FX 5200 (128MB) is too old for the OpenGL features or the drivers are, I think a patch is on the pipe line, hopefully.
Truth is I wouldn’t mind not having GPU support if only rotating canvas would work without it.
It’s officially stated that WinXP x64 doesn’t support OpenGL.
But I’ve found something useful in the adobe forum:
Q: Adobe says No OPenGL drivers in XP64? That isn't the case is it?A: No, it isn’t. OpenGL works just fine with the 32bit version, only the 64bit version does not support OpenGL.
Q: Not sure why they couldn’t implement at least the 32bit version of CS4 with OGL on XP64?!
A:
As per the above: They have. Your GPU just may not be supported, regardless, because Adobe considers it “old” (or takes it as a quick excuse to blame all the problems on you and walk away with clean hands, depending on how you see it). You can set a registry key to enable it (at your own risk). Save the below to a *.reg file, then double-click to import it into the registry.Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Adobe\Photoshop\11.0]
“AllowOldGPUS”=dword:00000001I don’t have my packages yet, but the settings file may also be on the installer disk along with other legacy compatibility registry hacks as already done in the past.
Mylenium
After installing Photoshop CS4 I created the reg file and ran it.
Voila, inofficial GPU support on Windows x64!!
Now my Photoshop is powered by the NVidia QuadroFX 4500 and uses 10GB of RAM.
Couldn’t find any issues so far!
Sweet Adobe!!
Hope someone else finds this info as useful as I did!
Best Regards
http://kb.adobe.com/selfservice/viewContent.do?externalId=kb406921&sliceId=2
I found this link by google search. I am using Quadro fx 1700 with OpenGL Drawing enabled in GPU settings of Photoshop CS4 under XP 64-bit. Smooth zooming and rotating canvas works fine on my 20-ish layers 160 MB 2K texture psds.
I did back up my registry before install the new one, but use that on your own risk as the webpage mentioned. 
hmm, i installed all the reg files and GPU is enabled but I still got the window when trying to rotate the document: “Could not complete your request because it only works with OpenGL enabled document windows” what I’m doing wrong?
Ok I found the solution. After isntalloing those rgistry files you need the newest Nvidia drivers . And it works
Thank you guys!!!
Thanks Jason for the additional info!
I’m curious to know if anyone saw any issues with this setup so far, since they mention:
“OpenGL on WindowsX64 has been minimally tested”
After some time I can only say that it’s slow (both on Quadro 1500FX and Geforce 8800GTX.) So for now it’s better to turn this option off.
I’m agreeing with that, does anyone have access to a brand spanking new machine with vista64 on it… Wondering if PS is still sluggish when trying to paint. Working on a Dual opteron 2.4ghz / 8gb of ram with a Quadro 4500 and paintovers on shots from a 5d seem really slow, even with just a couple of layers.
Is there a way to turn off the open gl sliding when you use the hand tool, I like the move and stop… not move and slide a little bit more… not playing skeetball?
I just disabled 3D Interaction Acceleration (Preferences/Performance/Advanced settings…) then it works fine, then I disabled Advanced drawing also and it goes even faster (other setting have no effect for me at all)
Btw speed is not at the same degree with CS3 yet I think but acceptable;
And here is a linkon Adobe, useful though! (also check the root directories) 
cpu: quad core
ram: 2G
graphic: 8800 GT/PCI/SSE2
Is there a way to turn off the open gl sliding when you use the hand tool, I like the move and stop… not move and slide a little bit more… not playing skeetball?
[Preferences/ Options/ Enable Flick Panning check box] you have to disable it,
thanks guys save me from going to vista:D working with geforce 7950gt nvidia card abit choppy on high res images but ok on most stuff.
Quadro 3700 here, latest drivers and activated GPU through registry. I’m experiencing some delay with the brushes.
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