Question About Lowering Power Limit % in MSI Afterburner

[professorY]

I'm currently running 2 Gigabyte Radeon HD 7950's and I have an issue with temperature in the upper tier card. The lower card can run at max speed (about 630 MH/s) and never touch 80°C but the upper card will blast over 80° (and even 90° if I let it) at much lower settings.

I've tried various cgminer configs and have my memclock down as low as it will go in MSI (though I haven't managed to get it to reduce lower by closing and re-opening MSI as some have suggested). The only way I've found to keep the upper card stable and around 80°C is to set the Power Limit % to -15 on that card. That seems to do the trick, but of course runs the card at ~300 MH/s.

My questions is: Until I get a better cooling system for the upper card (which is on order), am I doing any damage to the card by running it at -15% power? Insticntively it seems like that should be okay, but I thought I'd run it by your folks in case I'm missing something.

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[tom_o]

I'm currently running 2 Gigabyte Radeon HD 7950's and I have an issue with temperature in the upper tier card. The lower card can run at max speed (about 630 MH/s) and never touch 80°C but the upper card will blast over 80° (and even 90° if I let it) at much lower settings.

I've tried various cgminer configs and have my memclock down as low as it will go in MSI (though I haven't managed to get it to reduce lower by closing and re-opening MSI as some have suggested). The only way I've found to keep the upper card stable and around 80°C is to set the Power Limit % to -15 on that card. That seems to do the trick, but of course runs the card at ~300 MH/s.

My questions is: Until I get a better cooling system for the upper card (which is on order), am I doing any damage to the card by running it at -15% power? Insticntively it seems like that should be okay, but I thought I'd run it by your folks in case I'm missing something.

All the card is doing is clocking itself down - the 300Mhash isn't due to reduced power - its the reduced clocks. Run at lower speeds where you can keep it below 85.

Personally I run at 1085/1500 and -20 power, doesn't seem to affect me, still 88 degrees though! :S

[bushstar]

Perhaps this is dangerous information but I have had cards that are prone to overheat before and have change the temperature at which the card gets throttled in cgminer to 95 from the default 85 using --temp-overheat 95.

However, a practical and safer working approach I took today was to put a 10" desk fan right on to the cards. My 100C 7950 is now running at 75C on intensity 18. Perhaps a cheap desk fan could be your quick fix too?

[Geez]

How do you get 630 MH with a 7950? How far is it overclocked?

[professorY]

How do you get 630 MH with a 7950? How far is it overclocked?

The core clock is at maximum (1200) and the memclock is at minimum (625) and then I have power limit set at +20% (this is the lower, cooler card so I find upping the juice gives the boost). These are the Afterburner setting of course; I'm not using and cgminer tweaks for this one (I do when scrypt mining).

I get ~615-630 on both of them but the upper one gets hot so fast I can't keep it at that setting. But if not for the tempo, they both run at that speed.

[professorY]

Perhaps a cheap desk fan could be your quick fix too?

I have a cooler on the way for it.

This:

http://www.arctic.ac/en/p/detail/index/sArticle/502/sCategory/2182

Failing that, I also ordered a couple of risers so I might take the top card out of the mobo itself and mount it on the side of the case. The case I have has great airflow and has 6 fans built in, the problem is simply that the two cards are so tight together and the fans on one blows the heat from it into the other and drive sthe temp up. With only one card in I can run it for weeks on max and never go above ~72°C or so.

If neither of those plans works, I do have a decent fan I can use.