Bitcoin Forum

Alright so I have the following rig:
PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139010
Mobo: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131830
Case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811112300

I replaced a 5830 I had in it with 2x 6870's in crossfire. I use it for gaming and mining. Unfortunately I noticed that the first video card (closest to the cpu) has very little space before the second video card slot. The air intake must be affected because the first card can easily reach 103~ C. I'm not sure what to do. Currently, I have the rig right next to the AC unit and the cold air is keeping temps at 80C & 57C respectively. I can't have the AC blowing 24/7 otherwise I'll get pretty chilled but I'm scared to run both cards with the temps I've seen. Any ideas? I don't think the case is the problem really. There's plenty of airflow in there. I think the fact that the pci express slots are so close to each other is what's wreaking havoc on the one card. The other card has about 1-2 inches of space before the case wall and does just fine cooling itself off.

If you are running Windows (which I presume you are since you have mentioned crossfire), please download MSI Afterburner software. Then a) Lower the memory speed to 750MHz b) Try to lower the voltage to 1.05V and simultaneously bring down clock speed to 600MHz. and check the temps.

insert a bit of foam or something between the cards to force them apart.

Cut a 12cm hole in the side of Case and put there a 12cm fan or leaf the Case open.

You could try removing the shell of the cooler of your card.

I'd certainly recommend the earlier statements of underclocking and undervolting that GPU.
Since your using it for gaming and mining, doing it too much probably won't be an option, unless you are happy with constantly changing it back and forth. However you have got a lot of GPU power so it won't effect you that badly. It might help to do it to the other GPU's as well, as if you can't really improve the airflow you will wanting to reduce the overall heat of the case.

Many users of this forum have boasted a high mhash/s per watt by undervolting their cards infact. This is often a key point to keeping bitcoin mining profitable, covering the cost of doing it, by keeping energy usage/cost low as possible.
While overclocking might give you more mhash/s, it's not energy efficient for most cards.
Most find undervolting just abit reduces your wattage far more than the drop to your mhash/s rate in comparison.

I never use a case door,I always leave them off for cooling.Also,I use 4-80mm fans,1-bottom front of case blowing in,1-tie strapped wnere the case door would be (lower right corner) blowing in toward the lower fan & 1- just above the bottom front one blowing toward the vid cards,1-in rear of case blowing out.I also use a Zalman 9700 CPU heatsink/fan,it exhuasts towards the rear of the case & out.

Btw,I have 2-6970's in xfire,temp of upper card is 73c,lower card is 71c,consistantly  ;D

I don't underclock anything cause I play BF3 alot,just not while mining   8)

This is your fix for cards being too close together.

I guess there is a problem with the thermal compound on the chip. You better have a look for it. It's not the first time that i heard about this issue.

This is screaming, "WATER COOL, WATER COOL, WATER COOL, WATER COOL" :D

This won't work the way you might expect - the blower fan requires special ducting built into the shell in order to work at all. Without the shell, it will just blow air in all directions, and not through the heatsink.

I have a trifire (3x 5800 cards) in an Antec 300 case, and I ran into a similar issue: The top cards would get crazy hot! Underclock the memory as low as you can go, undervolt the core, put spacers between the cards at the back ends, and put a fan blowing right onto the cards. I run CGMiner with a target-temp of 70, and I only run into throttling when the ambient room temps go over 25 or so. Short of water cooling, that's about all you can do. :/

Thanks for your advice guys. I will definitely forcing the cards a little more apart and I'll look into undervolting or underclocking if it doesn't affect gaming too much. As for thermal compound. I know it's ok because if I swap the cards the other one starts doing the same thing. If I just use one there is no heat issue. Thanks for everyone's help again.

One last thing... How dangerous would it be to run the card at 100c~ for extended periods of time?

Killing option No1

Undervolting doesn't affect performance at all. It just lower power consumption (which lowers temps). When I game I just reset the Vddc core and mem back to stock. When I mine is when I tweak the cards.

100C?! Yaaa that'd be a bad idea.... You'll kill your cards within a matter of months.

Does that help with cards like the Sapphire xtreme 5830

I have that same card, so I'd be curious about this too. It's definitely a BAD idea to remove the covers for any GPU with a blower style fan, but for cards with a central fan, I don't know. I've also thought about cutting the grills on the vents of my cards that DO have blower fans. Just haven't tried it yet.

Here are some pics of that card:
http://www.overclockersclub.com/reviews/sapphire_hd5830_hd5850/2.htm

my reference cards with the blower style cooler work best IMO....

This xtreme card is giving me problems with temps... Fan has to be @ 100% or no dice...

The problem with those compared to a blower is they don't vent the hot air out the back. Does your case have enough exhaust fans?

I'm running mine at 940,300 @ 1.08V - 60-70% fan and temps around 68-73C. I have replaced the thermal paste with arctic silver and have a 120mm fan blowing right into all 3 of my gpus (the other 2 are blower style).

I wrote 5830.. its a 5850...

It makes no difference where the card is.. top or bottom pci-e slot... its always hot compared to the other card....


IMO its a cooler issue... I am going to remove the shell and see if that helps.

Ah gotcha. Those Sapphire 5830s and 5850s used the same cooler, so I'd still be interested to know if removing the shroud helps at all. Check your paste while ur at it?

Double spaced you're going to run into issues with one card being much hotting than the other. There's a few things you can do, some that have been mentioned already.

1. Put in a spacer to force the cards apart as much as possible.
2. Turn off crossfire in the ATI control panel when you're not gaming and change the clocks independently. Run the top card at something like 700MHz Core, 200MHz memory and 1.05V to keep the power draw down.
3. Make sure you have good airflow in your case.

I have a pair of 6950 1GB with unlocked shaders running at 900/200 in my main PC, and they hash like champs when I'm not using it to game. Just get lots of fresh air into the case.

I run all 3 of my 5800 cards with crossfire enabled, and CGMiner adjusts the clocks, mem, and VDDC independently. Is this different for 6XXX series cards?

CF enabled does NOT affect the GPU temp.
You only get low temps with TWO importend things;
Do lower the Voltage
and
Do ensure good airflow to your Case.
And check the thermal compound like i comment before.

I find I can't independently adjust the mem clocks down to 200MHz with CF enabled. It's notoriously difficult to break the link between core and memory speed on the 6xxx series cards though. It might be possible to clock each card independently and get mem clocks low with CF enabled, but I can't seem to get it to work.