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Author Topic: Better VRM cooling for 7970?  (Read 7249 times)
crazyates
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August 21, 2012, 05:10:27 AM
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I got a Gigabyte 7970 GHz. This card uses Gigabyte's Windforce "Triangle Cool" heatsink and tri-fan setup.

I have a box fan blowing the amazingly inconsistent New England air right at my comp, and another box fan on the other side of the room blowing out. Ambient temps are 15C at night, and 30C during the day.

During the day CGMiner downclocks to keep temps @ 70C @ 75% fan, but during the night it runs at stock clocks for 67C @ 55% fan, but my VRM temps are anywhere from 95-105C consistently.

It looks like the 3rd fan (right most when looking at the fans from the front of the card) blows air thru the heatsink, and onto the board directly where the VRMs (and their little tacked on mini-heatsink) are.

I'm used to my 58xx cards running their VRMs in the 80s, and while it's prolly fine, I don't like having temps this high. Any ideas on how to cool those VRMs better?

Edit: GPU-z shows 2 VRM sensors. One is always 95-105C, but the other is always much cooler, like 70-80C.

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August 21, 2012, 03:28:42 PM
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I have been working with two new gig 7970 windforces on a new rig as well. I have also been struggling to get the temp of the 2nd card down. It is a bit difficult because I plan to use this new comp as my main, so it is not a 100% devoted miner.

The first card is @ 1170/1020 ~ 690mh/s
The second card I set to 950/320, the under-clocking of mem seemed to help quite a bit, but it is still getting to 80-85, and then occasional spikes on the second card. I can't figure out why the second card is overheating (it actually has more room to breathe in my case than the first. The spikes have forced me to take out the 2nd 7970 until I figure out how to stabilize the temp.

I am using CGMiner and here is my conf:

Code:
{
"pools" : [
{
"url" : "pool",
"user" : "worker",
"pass" : "password"
},
{
"url" : "pool",
"user" : "worker",
"pass" : "password"
}
]
,
"intensity" : "9,d",
"gpu-engine" : "950,1020",
"gpu-fan" : "0-85,0-85",
"gpu-memclock" : "325,870",
"gpu-powertune" : "20,20",
"temp-cutoff" : "95,95",
"temp-overheat" : "85,85",
"temp-target" : "75,75",

"auto-fan" : true,
"auto-gpu" : true,
"expiry" : "120",
"failover-only" : true,
"gpu-threads" : "2",
"log" : "5",
"queue" : "1",
"retry-pause" : "5",
"scan-time" : "60",
"temp-hysteresis" : "3",

"kernel-path" : "/usr/local/bin"
}

Can you be more specific on your settings? We could trouble shoot this together with more info.

If anyone else has suggestions on fixes, please add to the convo.
crazyates
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August 23, 2012, 01:34:26 PM
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So I took the side of my PC off, and I get a little better cooling (the way the fans blow hot air out the top of the card).

I dropped my mem down to 325, and I get a little better cooling that way as well.

I've also been playing with -v -w and -I settings, and have bumped out an additional 20-25MH/s.

Right now, I'm sitting at ambient of 24C, core of 68C, and fan of 50%. But my VRM temps are 112C!

I might try just running my at higher speeds, say 65%?

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ssateneth
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August 23, 2012, 07:33:44 PM
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Have you try re-assembling your heatsinks? It's possible you have bad contact between the VRM and whatever is cooling it. I shaved off something like 15C from both of my VRM's on my one 5970 by using some thermal pads I got from frozencpu (the fuji extreme 11 watts/mk one)

crazyates
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August 23, 2012, 07:36:21 PM
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Have you try re-assembling your heatsinks? It's possible you have bad contact between the VRM and whatever is cooling it. I shaved off something like 15C from both of my VRM's on my one 5970 by using some thermal pads I got from frozencpu (the fuji extreme 11 watts/mk one)

I'm thinking I'll have to do that. It's a brand new card from Newegg, so I assumed there wouldn't be anything wrong with it.

I bumped up my fan to 65%, and while the core was ~63C, the hot VRM was at least under 100C.

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crazyates
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August 23, 2012, 11:59:04 PM
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So I took off the cooler and looked at the VRM heatsink. Tiny little thing...

It looks like there's good contact between the VRMs, the long skinny thermal pad, and the long skinny heatsink. I reseated it, and I'm still getting VRM temps 110+C (tho I really didn't expect it to). I might look into replacing the pads with higher quality stuff. Will this do the trick?

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ssateneth
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August 24, 2012, 01:07:05 AM
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So I took off the cooler and looked at the VRM heatsink. Tiny little thing...

It looks like there's good contact between the VRMs, the long skinny thermal pad, and the long skinny heatsink. I reseated it, and I'm still getting VRM temps 110+C (tho I really didn't expect it to). I might look into replacing the pads with higher quality stuff. Will this do the trick?

Same pads I used for my 5970. I even went the extra step of putting a tiny dot of shin-etsu x23-7783d thermal paste on each VRM chip. They now run significantly cooler than my other 3 "stock" 5970's, upwards of 10c. Bear in mind though that those thermal pads are a little tricky to work with. They're pretty delicate and the stiff plastic sheet that covers one side is difficult to take off without messing up the thermal pad to some degree. FWIW, I got both 1mm and 0.5mm pads to be safe, but you will likely only use 0.5.

crazyates
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August 25, 2012, 09:02:25 PM
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Same pads I used for my 5970. I even went the extra step of putting a tiny dot of shin-etsu x23-7783d thermal paste on each VRM chip. They now run significantly cooler than my other 3 "stock" 5970's, upwards of 10c. Bear in mind though that those thermal pads are a little tricky to work with. They're pretty delicate and the stiff plastic sheet that covers one side is difficult to take off without messing up the thermal pad to some degree. FWIW, I got both 1mm and 0.5mm pads to be safe, but you will likely only use 0.5.

I went ahead and ordered a sheet of 0.5 and 1.0 each on thursday.

So you put a tiny drop of thermal compound on top of each VRM, and then put a thermal pad? Whats the point? Wouldn't just the better thermal pad lower the temps?

I'm setting right now at ambient of 27C, and I bumped my fan speed to 90%. Core of 64C, and VRM of 99C. We'll see what the temps are when ambient drops 10C (down to 17C) tonight.

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ssateneth
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August 25, 2012, 09:38:34 PM
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I put the thermal pad on the heatsink (press a little bit with your finger while it still has the plastic on it, but dont mush it) and put a dot of -really good- thermal paste on the hotspots to ensure a good contact. I only did this because I didn't have much faith that the 0.50mm sheet would be thick enough.

crazyates
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August 28, 2012, 02:08:55 AM
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I put the thermal pad on the heatsink (press a little bit with your finger while it still has the plastic on it, but dont mush it) and put a dot of -really good- thermal paste on the hotspots to ensure a good contact. I only did this because I didn't have much faith that the 0.50mm sheet would be thick enough.

Alright so I got those thermal pads in the mail today. I took it apart, removed the heatsink and old thermal pad, cleaned the VRM heatsink with alcohol and q-tips, and cleaned the VRMs of any residue with a dry q-tip. I put a tiny (like TINY) dab of CM thermal paste on each little chip, spread it around, put the new thermal pad on the heatsink, and installed it.

All tests done at ambient of 26C.

engine:1100 - mem:325 - fan:90% = core:63C - VRM:93C
engine:1200 - mem:325 - fan:90% = core:65C - VRM:101C
engine:1200 - mem:325 - fan:65% = core:68C - VRM:113C

Pretty damn nice numbers for the core! I'm still gonna lock the fan at 90% tho, and maybe shop around for an aftermarket VRM heatsink.

EDIT:
I remembered I had a bunch of old RAM heatsink from years ago. The stick on kind? There are 7 black little chips sticking out the back of my card right where the VRMs go, so I threw 7 of the little heatsinks on the back of the card. Then I wedged a scythe 120mm fan between my CPU heatsink and rested it on my 24pin power cable, blowing down on the heatsinks. Here are new results:

engine:1100 - mem:325 - fan:90% = core:65C - VRM:87C
engine:1200 - mem:325 - fan:90% = core:67C - VRM:94C

It's a little hacked together, and good luck trying to do that to a 2nd card in CF, but it works! I'm happy with that.

EDIT #2:
Here is a Pic to see what I mean:


EDIT #3:
I FINALLY got voltage control to work in MSI AB. I ran a bunch of tests, at all mV settings from 800-1250, and found my most profitable settings:

mV:1050 - engine:1050 - mem:375 - fan:70% = core:52C - VRM:64C - Speed:615MH/s - Power:140W

Tips? 1crazy8pMqgwJ7tX7ZPZmyPwFbc6xZKM9
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