I currently run two GTX 460s in two machines, but am considering upgrading one to dual GTX 660 (not the Ti version).

In my current setup, each 460 has either 1GB or 768MB of RAM, and I run two MB WUs on each. This puts the GPU usage up to around 90%, so adding a 3rd WU wouldn't get me anywhere, even though there is enough room in video RAM for it. These cards have 336 (or so) stream processors. The 660s have 900+ processors, and 2GB of RAM each. Therefore, I assume processor use is again the limiting factor here; by the number of processors in the card, can I assume I can run 5 or 6 WUs simultaneously on each?

Any advice would be appreciated...

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I currently run two GTX 460s in two machines, but am considering upgrading one to dual GTX 660 (not the Ti version).

In my current setup, each 460 has either 1GB or 768MB of RAM, and I run two MB WUs on each. This puts the GPU usage up to around 90%, so adding a 3rd WU wouldn't get me anywhere, even though there is enough room in video RAM for it. These cards have 336 (or so) stream processors. The 660s have 900+ processors, and 2GB of RAM each. Therefore, I assume processor use is again the limiting factor here; by the number of processors in the card, can I assume I can run 5 or 6 WUs simultaneously on each?

Any advice would be appreciated...

Running my 670 at 3 per I was around 99%, with the 650Ti installed I backed it back down to 2 per and run around 94% on it with 99% on the 650Ti.

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Running my 670 at 3 per I was around 99%, with the 650Ti installed I backed it back down to 2 per and run around 94% on it with 99% on the 650Ti.

So, it sounds like aside from any speed increase due to the fact that the hardware is faster on the 660, I still won't be able to do better than 2 threads/660.

I guess I won't be spending the $200+ per card in the near future then!

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So, it sounds like aside from any speed increase due to the fact that the hardware is faster on the 660, I still won't be able to do better than 2 threads/660.

From what i remember of Fred's thread with his tool for determining what's best, 3 at a time on that card gives the best RAC. But if you only have 1GB of RAM, then you may get sluggish system behaviour if running other programmes that need a good chunk of video RAM. With a 2GB card, it wouldn't be an issue.

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Grant
Darwin NT

The 660's have 2GB VRAM, the 650Ti only has 1GB VRAM.

My 670 has 2GB VRAM.

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I have one rig with dual GTX660's (and another with a single GTX660). I run two instances per card, but 3 doesn't seem to yield much improvement. While the cards have plenty of ram to fit multiple instances their main limitation is the memory controller which seems to run at about 66% when running two instances and of course the GPU usage is around 99-100%. They are still faster than a GTX460 (and even a 560Ti) and power usage is less so they still make a worthwhile investment.

Link to dual GTX660 host here

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BOINC blog

I have one rig with dual GTX660's (and another with a single GTX660). I run two instances per card, but 3 doesn't seem to yield much improvement. While the cards have plenty of ram to fit multiple instances their main limitation is the memory controller which seems to run at about 66% when running two instances and of course the GPU usage is around 99-100%. They are still faster than a GTX460 (and even a 560Ti) and power usage is less so they still make a worthwhile investment.

Link to dual GTX660 host here

Hey - your RAC seems awfully low for all that hardware... (5K or so) have you been offline a lot recently?

My machines are 24/7/365 SETI only; I only check them a handful of times a day. One is GPU only - 2 x GTX460, 2 threads each, and I'm getting in the 25-28K range.

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Looks like he is mostly doing Einstein currently on those hosts.

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I have one rig with dual GTX660's (and another with a single GTX660). I run two instances per card, but 3 doesn't seem to yield much improvement. While the cards have plenty of ram to fit multiple instances their main limitation is the memory controller which seems to run at about 66% when running two instances and of course the GPU usage is around 99-100%. They are still faster than a GTX460 (and even a 560Ti) and power usage is less so they still make a worthwhile investment.

Link to dual GTX660 host here

Hey - your RAC seems awfully low for all that hardware... (5K or so) have you been offline a lot recently?

My machines are 24/7/365 SETI only; I only check them a handful of times a day. One is GPU only - 2 x GTX460, 2 threads each, and I'm getting in the 25-28K range.

Yes and no. They have been doing a lot of Einstein and they have been off (powered off) due to the heat, we're coming into summer down here in Australia and we have had a few hot days already.

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BOINC blog