Crossfire 7950s getting too hot

danielkuhlman · Jul 14, 2014

Hi all!

I recently bought another 7950 for my rig. My motherboard is a biostar ta990fxe board that has 2 PCIe 2.0 x16 slots and a PCIe 2.0 x4 slot. When both cards are in the x16 slots, my system get up to nearly 90 degrees under load. I have a storm stryker case with two front 120mm intake fans, a top 200mm exhaust fan, and the fan for my water cooled fx 8320 the back.

Temps are fine when the second card is in the x4 slot, but it's enough of a performance hit that it kind of makes crossfire pointless. I thought about buying riser cables, but I'm unsure as to how I would secure the card in place. I don't really want to spend more money on another motherboard if I don't have to...

And I bought a cooler master v850, so the power supply in the picture isn't the one in use

mrmez · Jul 14, 2014

With the cards so close they are definitely going to be heating each other.

Physically separating them would be good, but you can also attach a fan to the side of the cards.
a decent 140mm fan won't cost much and will definitely move a lot of hot air out of the confined spaces around the cards.

Overall however, the case setup is not great for heat.
You have a psu and 2 high heat cards producing hot air which seems to exit through your CPU rad. Also hard to see where the cool air comes in.

danielkuhlman · Jul 14, 2014

Cool air comes in from the front of the case. There are two fans that mount to the hard drive bays that bring air into the case. The panel has an acrylic window, so I'm not sure how I'd mount a fan on the window. There's an x4 slot below the secondary card, but it's quite a hit on bandwidth. It's a large case, and with the card mounted in the x4 slot the heat issue goes away, but the performance hit is quite stellar...

Also, there's a 200mm fan on top that pulls heat out.

Is there a way to use a riser cable to lower the second card and still secure it into position?

mrmez · Jul 14, 2014

Not sure about riser cables as I don't run SLI/XF.
I've always had a fan placed on top of my gfx card. Much easier to show with pix, but on a single card the fan is placed upright, leaning ~45 degrees onto the mobo & pointing towards it.

It wouldn't be hard to hang a fan covering both cards. Just use a paperclip and hang it off the water hose. You just need a temp solution to start off with to see if it makes enough of a difference. If it works, you can figure out a more secure mount.

coolcole01 · Jul 14, 2014

No the answer is to take a fanattach it to the side and have it point directly in the middle of the cards when they are in the top slots you need to get moving air closer to the chips

danielkuhlman · Jul 14, 2014

I have the two white 120mm LED fans that came with the storm stryker that were originally used as the front fans (replaced with cooler master sickleflow red LED fans). Would it be a good idea to mount one above the first card at a 45 degree angle towards the mobo and one below the second card angled so the fan pushes air out the back of the case? I'll eventually replace the fans if it works with something without white LEDs, but would like to know if this could lower temps before hand.

danielkuhlman · Jul 14, 2014

coolcole01 :

I thought about that. Is there a fan that would work best? Not sure what the RPM is of the stock cooler master fans, but they're 120mm fans. I can't mount them on the side as it has an acrylic window.

Should've went with the Storm Trooper instead of the stryker...

mrmez · Jul 14, 2014

Hang the fan upright, covering both cards so the air blows over them and onto the mobo.
The fan should be touching the cards to it can suck plenty of air in.

coolcole01 · Jul 14, 2014

Just get the best fan you can that can be quiet while pushing a ton of air i had two 7950's for a while they were awesome also have you tested each to see which is the hotter running card then putting it at the bottom

danielkuhlman · Jul 14, 2014

mrmez :

I'll try that in the morning. Is there a recommendation for size? Not sure how a 120mm fan will look, but if that's necessary to be able to use my second card to it's full potential...

danielkuhlman · Jul 14, 2014

coolcole01 :

The sapphire card runs hotter so I thought it would be best to place it at the bottom. The twin Frozr cooler seemed to be pretty good reading the reviews...

Noise isn't much of an issue since I usually use a headset. Even when I don't, I'm using an Azio Clicker mechanical keyboard which is loud as hell. Would an 80mm fan be sufficient? I have a couple 120mms on hand and a 200mm fan, but not sure how the inside of my case will look, as lame as it sounds.

coolcole01 · Jul 14, 2014

the 120 mm fans seen to work best for the direct cooling

danielkuhlman · Jul 14, 2014

coolcole01 :

Alright, I'll try one 120mm fan directly in between the cards, and another hanging over the first card tomorrow. I'll check temps and report back.

Would it be wise to remove the extra slot covering from in between the cards? Or will that just build up dust, hindering air flow even more?

coolcole01 · Jul 14, 2014

i always left mine open but i dont think it did much besides let in dust

danielkuhlman · Jul 14, 2014

coolcole01 :

Alright, worst case scenario I guess I can test both removed and in place as it takes two seconds to do so. I'll let you guys know how it goes tomorrow.

Thanks for the responses!

danielkuhlman · Jul 15, 2014

So, here's what I ended up with. It's ugly, but it keeps my top card about 10 degrees cooler. I would've liked to put the fan on the bottom right up more, but all the connections for my drives were in the way.

coolcole01 · Jul 15, 2014

10 degrees is huge good stuff

mrmez · Jul 15, 2014

Excellent, thats exactly what i was talking about. Now that you know it actually does something, you can figure out a more elegant and effective solution.

Crossfire 7950s getting too hot

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