Getting SLI heat out of the case

JackLeather

JackLeather

JackLeather

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19 Jun 2011
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Hi, i have just fitted a second 460 GTX (to my asrock z68 extreme4) and i am seeing the dreaded 'top card hotter than bottom card' effect.

Question. who has found a way to extract the heat from the case before it gets 'up' to the top card? is there some mighty slot fan than can do it? i'd rather avoid expensive after-market vga coolers.
 
depending on motherboard, you can put a PCI Exhaust fan thing inbetween them, which should exhaust any hot air coming from the card above it. Apparently very effecting but yet to see pictures.
 
Ive placed an antec spotcool behind my two cards, keeps them within a few c of each other.

http://www.overclockers.co.uk/showproduct.php?prodid=SY-000-AN

IMG_1803.jpg
 
I've also seen some guy that used cardboard and tape to place a fan on the outside, at the rear of his case.

It was awhile back, so I forget where I saw it.

But as you see from setters picture, it's a good idea to place a fan on the inside of your case, blowing air across both card. Same principle as inside the HAF-X case.
 
JackLeather said:
Good idea but the heats still in the case.

The 2x140mm on the roof might help but i just replaced the stock with a Megaflow - airflow isn't fantastic, but at least the noise is down on the stock fans.
Click to expand...
Are your cards reference cooled models that expel the heat out the back of the case? Some cards with custom coolers, (gigabyte soc's are an example), tend to dump a lot of heat into the case.

robin66 said:
But as you see from setters picture, it's a good idea to place a fan on the inside of your case, blowing air across both card. Same principle as inside the HAF-X case.
Click to expand...
Prior to fitting the spotcool, my top card ran 10c higher than the bottom one, now at idle theres a 4c difference, in game it's about 1-2c.
 
setter said:
Are your cards reference cooled models that expel the heat out the back of the case? Some cards with custom coolers, (gigabyte soc's are an example), tend to dump a lot of heat into the case.

Prior to fitting the spotcool, my top card ran 10c higher than the bottom one, now at idle theres a 4c difference, in game it's about 1-2c.
Click to expand...

My cards are the 'gigabyte 460 gtx 1gb oc' have the token holes in the slot at the back but I am quite sure the dump all their heat in the case. Like you I have a 10c difference. shame because everything was perfect with one card.

I will try a 140mm in a similar location to yours. Will let you know.
 
Before i got the spotcool, i simply hung a 120mm fan behind the cards, wasnt pretty but it worked, spotcool is just a bit neater looking.
 
Just did a quick check on goggle, and your cards do indeed dump there hot air into the case.

All I can suggest is that you fit some better fans to the rest of the case to help get rid of some of that hot air.
 
I added the extra fan. In Crysis 2 the top card got to 69C and the bottom 64C then they just stayed there for the rest of the game.

However when idle in windows 7 i see 52C for top and 34C for bottom.

If i touch the cards heat pipes the top card is indeed much hotter than the bottom.

i have tried swapping cards around to see if its an issue with one of the cards - but this made no difference, the top card (regardless of which i put up there) is 15C+ hotter than the bottom when sitting in windows.
 
What i am finding hard to get my head round is that the bottom card is almost cold to the touch but allegedly this heat is causing 18C increase in the top card. swapping the cards has not effect and the differential is similar.
 
JackLeather said:
What i am finding hard to get my head round is that the bottom card is almost cold to the touch but allegedly this heat is causing 18C increase in the top card. swapping the cards has not effect and the differential is similar.
Click to expand...
I don't think heat generated by the lower card is causing the increase in the upper card's temperature. It seems more likely that the upper card's access to cool air is being affected by the proximity of the lower card. This would explain why the upper card is overheating relative to the lower card.

This is the exact problem I had when I ran 2x 7800 GTX cards in SLI. Even when the system was idling the upper card ran a lot hotter than the lower one.

The only way around this seems to be a solution like the one above: fit an extra fan to force air directly along the upper card's shroud, thereby feeding it with the air it needs.
 
I have just read a thread elsewhere that goes like this;

My set up consists of two 27" asus monitors... I went to mess around with them and connected one of my monitors into my PC twice (from HDMI 1 and also plugged in HDMI output 2 into my second GTX 470) This made the GPUs think there was a third monitor, and allowed me to enable the new Surround display mode giving me a 5740x1080 resolution spanning all 3 monitors, or 3 different desktops. I tried both out.... and I noticed some very very interesting changes.

First and foremost I noticed my GPU temperatures decreased instantly, my top card immediately dropped back down to it's normal >40C tempearture at idle... and my performance was different in a couple of games, notably the new FFXIV Beta (it's late so I haven't tested much else yet) But I checked in my MSI Afterburner and noticed something, the GPUs are both running closer to parallel now in games, before they were not, one GPU would do 90% of the work while the 2nd wouldn't do much. I tried all sorts of settings to fix this but alas it seems the 258.96 drivers just don't like my dual monitor set up.
Click to expand...

what do you guys think of this?
 
I tried the fan. A 120mm at full speed directed at the back of the cards. this did indeed bring the two cards temperatures within a few degrees. This is excellent. I will definitely install something here like a spot cool (is it noisy?)

after that i started reading about 'GPU Runs at a High Performance Level (full clock speeds) in Multi-display Modes'. I have two matched LCDs on one card - the top card. I read that no matter what; a card will run at full 3d clocks when a second monitor is connected. If you watch the clock speeds in gpu-z etc in windows you will see that one card (with two monitors) stays at full pelt while the other is just coasting. This will means that extra work (and heat) is done by the top card even when not needed. So i moved my second display to the bottom card.

Within moments temperatures started changing. the bottom card heated up a little and the top lowered until they were almost identical.

Are there any drawback to running one monitor per card as opposed to both on one card. i remember something about windows requiring both on one card for something.

Next i removed the 120mm fan. Temps went up by about 5 degrees on the bottom card and 8 degrees on the top.

Looks like with a fan or not spreading the load between cards i preferable as no single card is hot. both are warm...This also give both cards the chance to downclock and conserve power and heat i think.
 
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