[RC5] gpu client

SideWinder sidewinder at kolumbus.fi
Wed Feb 18 04:00:05 EST 2009


On 18.2.2009 4:34, Kevin McCoy wrote:
> I have been overclocking my GeForce 8600 GTS and running the CUDA client
> for a couple weeks now. The GPU clock is running at 735 MHz. Mem clock
> is set to 2100 MHz.
>
> No smoke or flames. :-)

Smoke or flames are not the main risk, degradation of shader units so so 
that they will cause artifacts even at stock clock is. G84 already has 
thermal throttling, so getting it too hot to fail completely is unlikely.

> I keep an eye on the GPU temperature and it floats around 57-60C,
> depending on the ambient temperature.

My GPU keeps at 57 C for 38 C card ambient, 28 C system ambient and 22 C 
room temperature (even though those numbers would theoreticall violate 
AMD case environment specs, that's just a calibration issue since the 
airflow is over 150 ft^3/min. It's worth noting that your card, even 
while overclocked, uses about 65 % of my power (77 W versus 118 W). The 
good thing is that the "GT" cards of relatively recent middle class are 
still equipped with effective 2 slot coolers. I remember one 9700GT with 
a one slot cooler that heated to over 75 C at full load (with a 20 % GPU 
OC).

> The only problem with the CUDA client is that it makes the video
> performance pretty miserable, even with normal applications. I have to
> pause the client to get any work done. Maybe I need a faster video card
> and then throttle back the CUDA client :-)

I'm not sure, but I believe the problem is not so much in the client 
being "not nice" in terms of scheduling with the GPU, but that the 
driver has to reload lots of stuff to the card's memory when it switches 
between graphics and the CUDA work.

I'm not sure that can be avoided when any 3D application is running, but 
perhaps some driver hack could be made to help in speeding up the rather 
small 2D load by reserving more memory for the 2D side and improving the 
total frame buffer latency. At least to me it doesn't look like there is 
any difference between what is being drawn in 2D, the refresh rate just 
sucks when the CUDA Dnetc is running. The Vista Aero UI is another issue 
though.

Btw, what kind of keyrate do you get with the card and which core is the 
best for it?

-- 

 >------->- SideWinder -<-------<

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