Crossfire Heat Issues

[MG42Maniac]

Hi Guys,

I recently bought a 2nd 7850 to be able to run crossfire. Benchmarks showed it to be quicker than a 7970 and I've never had crossfire before so I thought I'd give it a go.

Fast forward to today and I've ran 3D Mark and scored 11,200 odd so they appear to be performing well. I did notice the fan kick in for the first time ever but assumed this was normal in benching with crossfire.

I started up Far Cry 3 and was met by flashing/flickering graphics as soon as the beginning cut scene was over. I played around with the graphics options but couldn't seem to sort it out. The fans were going hell for leather so i thought I'd check the temps.

One of the cards was 45 degrees with 20% fan, the other was 94 degrees with 100% fan! I though this was a misreading but both Trixx and GPU Z reported this value. I shut the game down and both cards returned to about 37 degrees.

Now, inside the case they are practically touching due to the fact the bottom PCi-E x8 slot is blocked by the PSU so I'm forced to use the top two PCI-E x16 lanes. I can't really get around this and I'm pretty sure one of the cards is dumping its hot air right on the back of the other.

Is there a way to get around this or is this a massive fail on my part for not researching things properly?

Specs are
i7 920 @ 4.2GHz
GIGABYTE GA-EX58-UD5
6GB RAM
2 x Sapphire 7850 2GB OC @ 1100 core / 5600 memory with 1.1v
120GB Agility 3 SSD
2TB Seagate
Asus Xonar D2X
650w Corsair PSU
HAF 932

Cheers!

 

[setter]

This is one of the pitfalls with xfire/sli, moreso on a board with tight spacing. Try using a more aggressive custom fan profile. On my cards i use a 1 - 1 fan curve setting, ie at 50c, 50% fan speed. Also, mounting a fan behind the cards blowing into them can help a bit.

 

[Marine-RX179]

Your only realistic options are:

a) Replace the board with one what has bigger gap between the top two PCI-E slot

b) Get another case which your PSU will no longer be blocking

c) Watercool the top card (though this option is a bit OTT).

d) Sell both cards, and go for a GTX670/7950 and be done with it.

 

[shankly1985]

If your case has a side fan, instead of in take try using it as an out take.
I noticed about 8c drop having the side fans out take the heat.

 

[setter]

What case are you using shankly, and how many side fans? 8c is quite a nice drop. Considering modding the side panel of my shinobi xl to take a side fan. My top card can hit as high as 78c, bottom one at 60c max. I have good board spacing but my cards are non reference types.

 

[shankly1985]

What case are you using shankly, and how many side fans? 8c is quite a nice drop. Considering modding the side panel of my shinobi xl to take a side fan. My top card can hit as high as 78c, bottom one at 60c max. I have good board spacing but my cards are non reference types.

Corsair Carbide 500r with two 140 fans. The name of the fans I completely forgot lol in work at the moment it can reply later with the model.

Also noticed with out take both cards keep within 2-4c of each other under load.

 

[MG42Maniac]

Cheers guys, looks like I'll have to sell them and go for a single card if I'm to keep my current set up. Do the newer Z87 motherboards generally have better spacing? I was tempted to upgrade to a 4770K and if the 7850's fit in the new motherboard I may just keep them.

 

[MeMeMeMe]

As a temporary measure, you could slide a piece of plastic or rubber between the cards, just to create a bit of spacing. Be careful not to do it anywhere near the fans.

It's surprising how little of a gap you need to create.

My first 5850 crossfire setup weren't identical models. The fan on the top card was brushing the bottom card and rattling (and temps were very high), till I slid in one of those rubber feet you get t put on the bottom of devices to create a bit of space.

Then I had the brainwave of switching the cards around and the problem went away.

 

[C64]

top card shouldn't be hitting 90+c even on xfire something is up which exact model are they ?

 

[shankly1985]

Add on to my post above.

The two 140 fans I using are Akasa Apache Black.

 

[C64]

test top card on its own see what temps you get if its way way over 60c something is up may need reaseating with better thermal paste
20% fan speed seems awfully low as well bung bottom one at 50% and top one at 75% see if any major improvement

 

[MG42Maniac]

Cheers for the advice guys.

I've just sold the 2nd 7850. I think come the end of the month I'll look to either upgrade to Haswell or may grab a 7970 if I see a decent one pop up in MM in the mean time.

 

[setter]

Add on to my post above.

The two 140 fans I using are Akasa Apache Black.

Cheers mate, ill look into getting the case panel cut. Id like to shift a bit of heat from the top card so that i can run both oc'd daily without resorting to crazy high fan speeds.