I've mentioned before, that I am running 64 bit versions of both XP and Ubuntu on PS3grid (GPUgrid). And I am also running BOINC 6.3.21 on all my boxes with no ill effects (yeti). Let me run over a few things concerning GPUgrid crunching

The 6.3.XX client is a custom BOINC client designed to utilize a GPU. The standard client series of 6.2.XX, is the non-GPU client that you should be using if you DO NOT plan on Boinc GPU crunching (on PS3grid). But, as I said, the 6.3.21 client seems to be running fine on my Win (XP64, W2K) and Ubuntu 8.10 boxes. The W2K box is a non-GPU box.


GPU Client development. (this is a snapshot in time, clients are changing weekly....)

The Boinc development team is working with Nvidia and PS3grid (GPUgrid) in an effort to devise a client that will allow GPU crunching WITHOUT using (or very little) CPU resources. This means for example: A Quad box (with 1 GPU installed) will be able to crunch 4 'normal' Boinc wu's and the GPU will be able to crunch 1 GPU wu at the same time, without having the GPU consuming CPU cycles. This is looked at as crunching 4+1 (4 cpu + 1 gpu wu's).

The goal is to have the GPU crunch at top speed, using it's own resources.

Windows
They are almost there with the Windows client. Using my Quad example from above, Windows will crunch 4+1 with no special input from the user (if crunching a GPU wu). But the GPU will be using ~15-17% of the cycles from 1 CPU (and it will not be running at top speed). Users can continue to operate their client at 4+1, and GPU wu's will run at reduced efficency for now. But, to get maximum GPU crunching speed using the Windows client, Users have to dedicate 1 CPU to the GPU. Right now, under Windows the GPU requires ~20-35% CPU cycles to crunch at top speed. So for best GPU results (shorter run times), some users are running 3+1 only .

Linux
But, they seem to have hit a home run with the Linux client . Linux crunchers can run 4+1 and will see the GPU using only 1-2% cycles from 1 CPU, and the GPU is running at top speed. This does not change even if you force the client to run 3+1.

Whew!

That being said. Boinc has released another NEW client (6.3.23) . If you like to experiment.... But it seems to be causing a few problems with Vista (GPU users). I'm going to wait this one out. I'm pretty stable now. Not to say that I won't try being a 'crash test dummy' with a future release...