Bitcoin Forum

Hi,
Air temperature is at 18 celcius (65f). Adapter 0 in one card is jumping right up with heat - I have it downclocked to 600 including the other adapter on this card and it keeps going up and up in temp.

Another one of my machines is the same with adapter 4 as well.

Any ideas on what to do?

Thanks very much.

Get a toothpick, put a small piece of mylar on it like a little streamer.  Go around your case using it to look for any airflow voids, watch for it to flap around in the wind (the toothpick isn't conductive so you can poke it into unused slots) .  I had a situation on one case where how the HDD cage + cabling + cards were arrayed i had a HUGE airflow void across one of the cards that was causing major thermal issues.  Be sure to close the case up each time and watch it, dynamics of airflow with the side panel on/off are very different.

Ideally you want good flow over both the front and back of all cards. If your airflow seems fine everywhere, look at the "flow" of the air in terms of:  hot air vented from the PSU is then being sucked into the video card for example, do you have anything dumping its heat directly on to something else?

The easiest thing to do is just go caseless if you don't mind how it looks. Otherwise, you may have to get more fans. I have 3x140mm, 1x120mm, 1x230mm (side fan), plus a small box fan pointed at the 230 outside the case. This keeps the cards pretty cool, but it is a little over the top fan-wise. With a case it seems you have to flush air through like crazy to keep the cards cool.

at what temps are your cards forumuse84?

The majority of them are running at 75 or less celcius. Some of them particlary adapter 0 and 1 on one rig. Those temps go through the roof. The side fan on the HAF x doesn't cover these cards as well as the rest though - The back of the card does not get cool air blown on at all.

Strangly enough on a second rig adapter 4 goes red hot as well.

When I say red hot I mean either having to downclock to 600Mhz or switch off the adapter completely.

But what temp is "red hot"??
75°C for the majority is already considered "cold" for a 6990, with most people reporting temps >80°C

I don't have any 69XX cards but 58XX cards throttle the clock rate at 100°C, so I would assume that 10-20% below that emergency threshold would be in a "mostly safe" range.

I would experiment with directing airflow into the intake end of the cards. But keep it gentle, with large fans limited to slow speeds to avoid creating turbulence that works against the flow through the GPU coolers.

Side question: Smoke is good for making airflow visual, and can be seen in some hardware demo videos as well. Does anyone know if there's something like "aerosol smoke" that can be bought for scale experimenting? Cigarettes don't seem to cut it... :P (but a lighter can work for checking if there is any airflow at all, like with PSU exhausts and such)

Right up to 85 and rising slowly but surely. It's way hotter than the rest of the adapters. I thought the 6990 throttled itself down at 90 degrees.

Do u use the airtunnel and have u added an additional 200mm fan on top?

Whoops I just started a new thread on this issue after forgetting about this thread. I need to set email updates on my threads. Anyway check it out here http://forum.bitcoin.org/index.php?topic=30719.0

Can you tell me what you mean by airtunnel? I tried adding an additional fan at the top but it didn't make a difference!

the HAF X comes with a black things that sits on some part of the gfx cards, mounted on the harddrive case. this can hold another fan which then pumps air straight onto the cards. it does not fit on a card that sits in the first pci-e slot, but maybe it helps (if the 6990s aren't too long to put that thing in).

or you just strap an additional 120mm fan with high airflow (like an enermax magma which runs with a pretty low noise level) onto the hdd cage, pointing the air onto the gfx cards

6990 are running particulary hot but they seem to like it. mine were running on stock speeds at 92° just fine when it was blazingly hot with 37° outside 40° ambient temp in the basement. afaik they downclock themselves at 100° not with 22° outside they settled at 79°