SLI setup....pick which card to use in Single GPU mode?

biggawhat

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So here is my question. Is it possible to choose which GPU on your mobo is being used when running a program using only 1 of the 2 cards. For example, Rage runs terribly in SLI so I change its profile to Single GPU in the Nvidia control panel. This fixes the problem, but it always picks the same GPU to use, which happens to be the GPU which runs hotter of the two. While cooling is another seperate problem that I'm dealing with, for the time being, is there any way I could force the game to use the other card...the one that runs cooler? Thanks
 
Solution
One option (if you are fairily tech savvy) would be to take off the heatsync, clean everything up, apply some fresh thermal paste, and re-seat the heatsync.

The thermal connection can degrade over time and you might be able to bring your temps back down with a fresh application of thermal paste.

blade061188

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Easy, if you aren't running SLI, the card used will be the one that is hooked up to your monitor.

Switch the card your monitor is hooked up to and you will be all set.

However, when you enable SLI again, I believe you will need your monitor to be plugged in to the GPU closest to your CPU (which is probably the hotter one) but I am not sure on that issue.
 

biggawhat

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Haha oh yeah, why didn't I think of that. Was focusing on software implemented fixes too much I guess. thanks :). And yes I'm pretty sure the hotter card is closer to the cpu. Its reaching 100C under load at 100% fan. Not good. Not sure why though, its clear of dust, has new TIM, decent airflow as far as I'm concerned. Seems like idle temps have slowly been rising too. System is 4.5 years old though, so maybe cards are just crapping out.
 
If you do want to select only one card to play the game and you want to rotate then you may have to select one card to be dedicated to graphics and see if it will use the other to play the game and if that works for you then you can rotate the selection. You may also have to switch the monitor cable. The other option since you are having a problem with one of the cards is the switch the cards and then that way the cooler card will be in the first slot.
 

biggawhat

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I feel like its not an inherent difference between the cards that is causing the temp difference, but just their position on the mobo. The cooler one has better access to intake air, so thats why it stays cooler. Switching the cards on the mobo then, probably wouldn't make a difference. Granted I haven't actually tried it, so maybe I will when I get home.
 

biggawhat

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Its two 8800GTX's so my system is relatively old...but I'm trying to milk as much as I can out of them before having to build a new system. Anyways, they aren't overclocked. I feel like the temps have been slowly rising for the past year or so. Prior to that I'm not sure as I didn't really get interested in building/fiddling with my computer before then, so I never checked. Within the past month both cards seem to have increased their idle temps by ~4C, even though ambient temperature has decreased
 

blade061188

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One option (if you are fairily tech savvy) would be to take off the heatsync, clean everything up, apply some fresh thermal paste, and re-seat the heatsync.

The thermal connection can degrade over time and you might be able to bring your temps back down with a fresh application of thermal paste.
 
Solution

biggawhat

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I did that for one of the cards (couldn't for the other b/c screw was stripped and I couldn't open the card...and haven't bothered trying again since) Didn't seem to make any difference in the temps for the one card, though.
 

biggawhat

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I just tested this and when switching the cards on the mobo the other card still reaches 100C
 

biggawhat

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Essentially when either of the cards is in the bottom slot, its cooler, and when either card is in the top slot it is hotter (100C under load) so it seems its not a specific defect in one of the cards. I did manage to (after much twisting and grunting) get the stripped screw out and get the case off of my 2nd card and reapplied TIM. I then went back and checked the TIM on the first card, and realized I applied it very poorly, so I reapplied it there too. This seems to have dropped the idle temps on each card by ~10C (hopefully more once the TIM settles). So now the card is only reaching 90C under full load...which is much better but not great
 

blade061188

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Yea, that is better.

One of the problems of a double card solution is the bottom card will cut off a lot of the airflow to the top card, so the top card always tends to be hotter.

Hopefully the re-seated heatsyncs help your temps too. Those cards would be fine to be running around 90C. It is a little hot, but they should be Ok. I had 2 8800GTS before my current rig, and they were typically in the high 80s, and they are still kicking today. (but not in my main rig haha)

If you have what you need from the forum, please close the thread (by selecting a best answer) Otherwise, feel free to ask more questions!