Need help with Crossfire - High temps

[Christopher Shaffer]

I just purchased a 2nd 7870 to pair up with my Sapphire 7870 GHz 2GB OC. I purchased an Asus 7870 DirectCU II v2.

They seem to work fine in Crossfire, but I'm running into a heat issue all of a sudden with the Sapphire.

I left the Sapphire as the primary card and set clock rates to stock on both cards (note: the Sapphire GPU/Memory stock clock is 1050/1250 - so 5GHz effective - and the Asus is 1000/1200). When running FC3 I found that the Sapphire got up to 76C; running alone this card has never breached 67C based on my HW Monitor records. The Asus never got above 59C, even though in FC3 it was at 98% GPU usage.

I'm wondering if swapping them would take this down a bit? I actually shut down FC3 once I saw the temp hit 75 on the Sapphire to prevent any issues. It dropped very quickly, but I'm sure it would have gone higher.

Any suggestions?

 

[pauls3743]

When you crossfire/SLi you are adding another heat source to your computer and interrupting the current airflow through the case. The temperature of the primary card (the one nearest the cpu) will get hotter because the air to it will be pre-warmed by your second card as well the airflow being restricted by the closeness of the second card. The second card won't have the same problems as it is still unobstructed.

Make sure you create as big a gap between the cards as you can so the airflow is restricted as little as possible. As a lot of the gpu coolers these days exhaust their hot air back into the case I would also suggest looking at the airflow through the case.

 

[Christopher Shaffer]

When you crossfire/SLi you are adding another heat source to your computer and interrupting the current airflow through the case. The temperature of the primary card (the one nearest the cpu) will get hotter because the air to it will be pre-warmed by your second card as well the airflow being restricted by the closeness of the second card. The second card won't have the same problems as it is still unobstructed.

Make sure you create as big a gap between the cards as you can so the airflow is restricted as little as possible. As a lot of the gpu coolers these days exhaust their hot air back into the case I would also suggest looking at the airflow through the case.

While I don't doubt this is true, the temperature was clearly going to continue to increase had I not shut FC3 down. I don't think the 2nd card alone explains a nearly 10C increase in temps or the fan running overtime.

I had the single Sapphire running at 1150/1275 GPU/Mem before adding the 2nd card and have now downclocked it to stock. It never got above 67C with those settings. If anything, it should have remained nearly the same.

 

[wanderer11]

10C sounds about right. I have two Sapphire 7870s and the top one runs about 10C hotter. Download/install MSI afterburner and set up a custom fan profile. I set mine up just fast enough so I normally can't hear the fans. Also, you can have both cards running at different speeds. One of mine is 1000/1200 and the other is 1050/1250. It runs perfectly fine that way.

 

[Christopher Shaffer]

10C sounds about right. I have two Sapphire 7870s and the top one runs about 10C hotter. Download/install MSI afterburner and set up a custom fan profile. I set mine up just fast enough so I normally can't hear the fans. Also, you can have both cards running at different speeds. One of mine is 1000/1200 and the other is 1050/1250. It runs perfectly fine that way.

So a few things:
1) What kind of temps are you getting under load? Can you compare running FC3? Oddly the temps are a bit lower running near-Ultra on BF4

2) My fans are clearly audible and ticking up in speed, as they should, with heat. I'm concerned if I manually set the fan speed, it won't run high enough if needed. Can you tell me your MSI AB settings?

3) Is the higher clock speed on the main card or the 2nd card?

4) I have a side-panel fan blowing directly in at the cards. Can you speak to the additional case cooling you're using?

Thanks!

 

[wanderer11]

1.) I don't have FC3. My fans run around 50% gaming so I see temps around 60-65 C on the top card and 55-60C on the bottom.

2.)This will depend on your case airflow too. You have slightly different cards too. Just play around with it. I think mine goes 45% at 50C, 50% at 60C, and goes up steep from there. I don't remember exactly.

3.)Higher clock is second card.

4.) I only have the two stock fans in my HAF 912. Nothing fancy. The sidepanel fan is a good idea.

 

[Christopher Shaffer]

1.) I don't have FC3. My fans run around 50% gaming so I see temps around 60-65 C on the top card and 55-60C on the bottom.

2.)This will depend on your case airflow too. You have slightly different cards too. Just play around with it. I think mine goes 45% at 50C, 50% at 60C, and goes up steep from there. I don't remember exactly.

3.)Higher clock is second card.

4.) I only have the two stock fans in my HAF 912. Nothing fancy. The sidepanel fan is a good idea.

Thanks. This is actually very helpful. I will try swapping the cards as the main card stock clock is a bit higher than the other and the Asus has a better cooler. I'll see if that helps.

Also, from what I've been reading, ~80C is fairly normal for the top card at max temps. So if the Asus runs cooler by default, I'll put it on top and the Sapphire 2nd. Maybe nice to have a slightly faster card on the 2nd anyway.

I do have a side-panel fan, but have always been unsure if using this as intake or exhaust is best. I'm using what was originally the top exhaust as the side fan; they're all 120mm. This is a new build so I haven't been able to add/move fans too much yet; still experimenting. My current setup is like this:

Again, everyone's input is appreciated and any advice is welcome.

Thanks!

 

[Christopher Shaffer]

So I wanted to post back and say that I was able to solve this issue and it was fairly simple.

I took two main steps:

1) I changed the side fan to an intake (I was incorrect w/my pic above; it was actually setup as exhaust which worked well with a single card but not with the x-fire).

2) I removed the Sapphire cooling unit and discovered that
a) The unit was not attached at tightly as it probably should have been... I'll give them the benefit of the doubt here as it could shake loose in shipping and
b) The amount of thermal paste applied would be sufficient to ice a cake.
c) The copper surface of the heatsink had noticeable hairline grooves from whatever they used to buff (if you could call it that) the surface. I went at this with some 1000 gauge steel wool and it's now smooth as a baby's bottom. I reapplied a *small* amount (about the size of 1/4 of a pea) of thermal paste and reattached the cooling unit, careful to fasten it down in a diagonal fashion and torque it just enough to get a nice, snug fit.

My idle temp on the Sapphire in Crossfire mode was about 30-31, and as I said before, temps were nearing 80C. I shut FC3 down at 75-76C, but it eventually registered 81C on HWMonitor.

With the simple changes I have an idle of about 26C and FC3 on Ultra, HBAO and MSAA x4 and it didn't pass 74C after a hour of gaming. It hit the previous high before I had taken a step.

 

[pauls3743]

Glad to hear you got it solved.