GPU temps in SLI

I recently upgraded my PSU (now at 900w) and added a 2nd GTX260 c216 video card for SLI. The performance boost is great, but one of the cards runs MUCH hotter than the other. The original card (the top card in my case) would max at 65c during hours of gaming (COD5 for example). Now I've added a second card, both cards have the same clock speeds, both fans are locked 70%, and the 2nd card maxes at about 60c (screenshot attached), but the original card now hits 85c!!! A few days ago after an hour of Metro2033, it got as high as 90c! Why is there suddenly such a huge difference in temps? Why does the original card run 25-30c hotter than it did before the SLI? The new card has 'normal' temps. I realize it's summer now, and my system temps are hotter on the whole: my CPU now maxes at 53c or so, and it never got over 45c during the winter months, and it only hit 45 when running CPU stress tests. So, I have no problem with a 10-15c jump because it's warmer weather now, but a jump of almost 30c is a bit troublesome. The screenshot attached is from about 2hours of playing "Sniper: Ghost Warrior" with all in-game video settings at "high" or "very high".

(I found this article online, and I'm thinking of using 2 slim 80mm x 15mm fans on each card; I'd have to use slim fans due to space constraints with SLI)

 

Oh yeah - I have great cooling: a front 120mm fan blowing inward, a side 120mm fan blowing inward at the top video card, a rear 120mm exhaust fan, and two 120mm fans on top also blowing outward (exhaust). The PSU is bottom mount and I have installed so it doubles as an exhaust fan, drawing air from inside the case and blowing it out the back. The case is a NZXT Beta EVO (link: http://www.nzxt.com/new/products/classic_series/beta_evo) and the entire front panel and most the rear panel is mesh for increased air flow.

(I figured I'd add this info in case someone needed it later )

 

I have a pair of GTX470s in SLi and the same result.
What i think is the problem is that the cards are so close that one card is drawing warm air in from the other.
My lower card runs at 55C and the upper runs 86C, i think the only way to get them the same is with the water pack for the GTX series.

 

Hi BILLMC! Weird that our temps are almost identical! Ya know, after I posted, I started thinking that the top card is most likely sucking in warm air directly off the lower card, so you just verified what I was thinking. I'm thinking of trying the things in this article that I linked to earlier just to see how much (if any) difference it will make. I can get slim 80mm x 15mm fans for $3 each, so investing $6 and 30min seems OK for 20c temp drop! If I do it, I'll be sure to post my results!
:-D

 

I think you are onto something there but have you got enough room between the cards to fit it to the upper card (i don't) unless i use the two pci slots that are designed for cards 1 and 3 if i use 1 and 2 there is only about 1cm between them.

 

Same here with my pair of 9800GT's, I even switched them because the lower one was newer but the same thing happened, hot on top. Not SLI'd either as I don't need that.

 

My motherboard is an Asus M4N72-E (link: http://www.asus.com/product.aspx?P_ID=5tWNOaMAxGs1FXIQ&content=specifications) and has just the two PCIe video slots, and they're spaced fairly well so I think that a couple slim-line 80x15 fans will fit. Picture of my mobo: http://www.asus.com/websites/Global/products/5tWNOaMAxGs1FXIQ/LtoKhr0uPEW0Ueqk_500.jpg

I'm also thinking that I'm gonna drop another 120mm fan on the other side of the hard drive cage; there's already a 120mm mounted to the front of the case that blows in across the HDs. If I add a 2nd fan on the opposite side of the HD cage blowing in the same direction, it will blow right between the two video cards . . . now that I'm thinking about it, maybe I'll do that before I mod the cooler on the top video card. If it lowers my temps by even 10-15c, I'll be happy!

roflmao YEAH! I did the same thing!! I thought maybe one of the cards was faulty or something!!! LOL

 

Hmmmmm . . . . my link above to my mobo specs doesn't seem to be working anymore (it worked yesterday :confused ), and the USA Asus site doesn't even list my board at all! Oh well . . . if you're truly interested (yawn), use the Asus Global site and search the model number M4N72-E.

 

I did some research finally (I'm slow), and discovered the stock 120mm front case fan was only blowing about 40cfm, and it was behind a foam and mesh dust filter, so I'm sure the output was even less... I swapped it for a 85cfm fan. Also, my side case fan was also behind a dust filter (loose weave foam). I removed the foam piece, soaked it in very hot tap water and stretched it out almost a half-inch on each side, then pressed it between paper towels between two thick phone books for a few hours until it was dry. I trimmed it so it fit back in its mount, and it still works GREAT at catching dust and cat hair, but now A LOT more air is getting through! Now, at idle, my top card is actually a couple of degrees cooler than the bottom card (the bottom card is only about an inch from the PSU), and under load it's only about 3-5c higher. Previously, it was 20c higher!!! I think the main difference came from swapping the front case fan to one with higher output....

Just an update in case anybody was interested (*yawn*).

 

My own GPU was running hot (I have only one) and the little cooling fan, down inside the heatsink finally burned out. Not having a replacement fan that would fit inside that heatsink, I took an old K6 CPU cooling fan and hot-glued it down on top of the GPU heatsink and now the GPU stays cool as a cucumber.
The replacement fan is almost double the size of the original fan and works just great. If it ever fails, I'll just snatch it off and replace it with another one.
(I have several of them in my junk box)

Replacement GPU heatsink fan:



Keep it cool and keep it running!

The Shadow :cool

 

I'd bet that it works even better than the stock fan did! Since I made some improvements in my fans (see post #9 above), and completely cleaned my top SLI card, things are much cooler now!

 

umm

gpus blow hot-air ?
you are probably choking the cards ?
DUH ?
,
anything below 102c is fine

 

Too hot?:confused
You don't need expensive laboratory grade equipment to tell.
Just put your finger on it and if it makes you cry out in pain, it's too hot!
Anything that you can touch without pain or even discomfort, is OK.

Fans in general are little dirt magnets. Keep'em clean!

:cool