6950 2gb high idle temperature vs 1gb

[kajabla]

Hi, all. I've recently become the owner of a used 6950 2gb, a Sapphire dual-fan version, and it's running idle temperatures surprisingly high compared to my old OCed 460 1gb: 43-45C with ambient temps a little under 20C. This is with two displays going, but I only have simple webpages (like Tom's) open and no major background programs that might be sucking GPU time. The card is in an In Win Dragon Slayer with stock fans (1x140 + 1x80 in the front, 1x140 at the top and 1x90 in the back; Newegg leaves the front 140 out for some reason).
I thought this was odd, so I did a little Googling, and it turns out Bit-Tech came up with similarly high idle temperatures for the 2gb version, but not for the 1gb card: http://www.bit-tech.net/hardware/2011/02/11/amd-radeon-hd-6950-1gb-review/8
Why would this be? I was under the impression that the extra VRAM was the only significant difference between the cards (besides the possibility of an unlock, but that's not relevant).

 

[Earnie]

As i type,also on dual monitors and crossfired sapphire dirt 3 edition 2G 6950's(unlocked shaders)my primary card is idling at 31'c(ambient temp around 21'c).secondary card at 24'c)
So,No,they do not idle at higher temps,at least mine dont.

 

[swifty_morgan]

the key word is "used". who knows what the person before you did to it. could have been push beyond it's limits and is on it's last legs.

you said it was unlocked. did you try moving the BIOS switch back to "normal" ?

have you pulled the heat sink and tried cleaning up and reapplying thermal paste ?

 

[abbadon_34]

same card, mine is 40c idle, but i do have tons of stuff in my case

 

[kajabla]

The last person is a friend, and he never overclocked it. The card has never been unlocked; I mentioned the possibility only as a difference between the 1gb and 2gb versions.
I gave the card as thorough a cleaning as I could with compressed air when I first got it. Dust isn't a problem. Do you think thermal paste could become an issue in a couple of years of normal use?

Very interesting, Earnie. What's the specific model of your card?

 

[renz496]

did you use two identical monitor? the rise idle temps on the radeon are to be expected when two or more monitors are connected to the card. it was caused by increased idle clock compared to single display idle clock to prevent flickering on the second monitor. the same was true for nvidia cards. but some users claim that they were able to enter proper idle clock with gtx460 even using more than one monitor. however the monitors must be identical and some adjustment are needed if necessary to make it work properly.

 

[kajabla]

Hey, that did it! The displays are 1920x1080 and 1280x1024. I just disabled the smaller one and my GPU temperature immediately dropped to 35C. The core clock dropped from 450 to 250mhz.
I don't remember whether my idle temperatures changed on the 460 when I added the second monitor. Maybe I'll experiment sometime.
Thanks.

This still leaves the question of the 1gb vs 2gb open. Wouldn't you expect this multi-monitor phenomenon to happen on the 1gb card too?

 

[kajabla]

Best answer selected by kajabla.

 

[Pinhedd]

Hi, all. I've recently become the owner of a used 6950 2gb, a Sapphire dual-fan version, and it's running idle temperatures surprisingly high compared to my old OCed 460 1gb: 43-45C with ambient temps a little under 20C. This is with two displays going, but I only have simple webpages (like Tom's) open and no major background programs that might be sucking GPU time. The card is in an In Win Dragon Slayer with stock fans (1x140 + 1x80 in the front, 1x140 at the top and 1x90 in the back; Newegg leaves the front 140 out for some reason).
I thought this was odd, so I did a little Googling, and it turns out BitTech came up with similarly high idle temperatures for the 2gb version, but not for the 1gb card: http://www.bit-tech.net/hardware/2011/02/11/amd-radeon-hd-6950-1gb-review/8
Why would this be? I was under the impression that the extra VRAM was the only significant difference between the cards (besides the possibility of an unlock, but that's not relevant).

Running a second display will raise idle temperatures by quite a bit, the chip has twice as much work to do. If I turn my TV on my primary 7970 will go from about 35 idle to around 43 idle, core clocks will be higher as well which will contribute to the higher temperatures. This is nothing out of the ordinary and is nothing to worry about. GPUs are workhorses and are designed to survive temperatures well in excess of 100 degrees centigrade.

 

[kajabla]

Any thoughts on the odd Bit-Tech results, then?

 

[Pinhedd]

Any thoughts on the odd Bit-Tech results, then?

the rate of heat transfer is exponentially proportional to the temperatures at each extreme of the temperature gradient. This means that it's much easier to dissipate equivalent quantities of energy from an 80 degree surface into a 30 degree environment than it is to dissipate the same quantity from a 40 degree surface into the same 30 degree environment. This is why components reach high load temps, eventually the energy dissipated into the environment will reach equilibrium with the energy transferred from the heat generating silicon to the heat sink. This is the same reason why a heat generating component can never be cooled below the temperature on the extreme side of the temperature gradient, and unless you're using a phase changer this is going to be the temperature of the ambient environment.

On a different, but related note, not all chips are manufactured equally. Bit-Tech's test indicates that the 6950 1GB draws 9 more watts than the 2GB version while idle and 22 watts under load. Similarly the 2GB version is a full 10 degrees hotter while idle and 8 degrees hotter under load. This really points to the 2GB version having a shitty heat sink, it doesn't dissipate the heat as effectively. Since there's only a very tiny relationship between temperature and power draw we can deduce that two identical chips (without any form of power control) with different heat sinks will put almost the same amount of heat into the environment over a period of time, one just does it more efficiently.

 

[kajabla]

Thanks for the physics lecture . Yes, I'm familiar with basic thermodynamics. I took physics just last year
I do think it's odd that the review didn't note the discrepancy.
Here's another with an equally high temperature on the 2gb version (though mine's lower now): http://www.legitreviews.com/article/1488/17/

 

[renz496]

This still leaves the question of the 1gb vs 2gb open. Wouldn't you expect this multi-monitor phenomenon to happen on the 1gb card too?

if you're talking about multi monitor gaming then that's where the trouble is. with 3 monitors you're going to push lots of pixel and that require quite hefty of memory and gpu horse power. by today standards 1GB is the bare minimum to have if you're running single 1080p monitors.

 

[kajabla]

I'm talking about the difference between the two cards' idle temperatures. No gaming involved.

 

[Earnie]

Very interesting, Earnie. What's the specific model of your card?

mine are these:

http://www.sapphiretech.com/presentation/product/?cid=1&gid=3&sgid=1041&pid=1235&psn=&lid=1&leg=0

 

[kajabla]

Mine's the same.