Bitcoin Forum

I have a machine with 4x 6950s and the heat cascades from the bottom card (~75'C) all the way to the top card (~100'C), as each card sucks air off the back of the card below it, which pre-heats the intake air, and makes cooling the core less efficient, so the core is always a higher temp than the card below it.

Are there any tips or tricks to cooling cards that are sandwiched together?

I've already inserted rubber grommets between them for an extra few mm of spacing, and removed the metal face plates off of the input connectors to improve exhaust capacity.

Anything else I can do?

I use watercooling with my 5870 "sandwich". Core Temp was like yours with standard fan cooling. With watercooling the core temp is between 48 and 52 centigrades from bottom to top of the sandwich.

Are you running the cards in a case? Have you tried adding a side fan if possible?

I wish I could justify the extra cost of water cooling, but with with the difficulty making mining that much harder, and the crash in value, there's just no way I can spend $80 per block per card, plus pump and rads.

I'm looking for solutions that need no more than duct tape and WD-40...


I have 4x 120mm fans at the front of the case (the old CM Stacker) and the centrifugal fan blowing across the motherboard.

I will try adding an 80mm fan aimed at the top two cards, but I'm guessing the cross wind will just carry that flow straight out the back exhaust.

How much did you pay for the water colling system? Is it realy worth it?

As you asked for a quick and dirty solution: have you tried putting two 120mm fans onto the sandwich? They should blow between the cards in order to support the cards fans.

Edit: I see you already did...

that only insulates each card from each other. the heat produced and dispersed is still the same, so that doesn't fix the problem at all

You can wedge something small (1-1.5cm thick) between them, to hold them apart, then as others said, mount 2 120s to the sandwich!

lol, your house will be full of asbestos if you do that.
that will stress the PCB/PCIe connectors

Yank that mobo out of the case, build a two-tier chassis out of angle aluminum or wood, and take two of the cards off the mobo and put them on adapter riser cables.  That'll free up a lot more space between cards and give you a lot more room to run fans.  If you already have a bunch of spare wood laying around like I did then you're only out the cost of the cables, which ran ~$30 in my case.

Asbestos has been illegal for over 30 years in most countries, google it.

If you go into a room with asbestos (let alone spray some in your near vicinity) you are increasing your risk of fatal cancer by a factor of about 100,000. Not really a good idea.

No, Jack, don't discourage asbestos use.  If other miners get mesothelioma then that leaves more blocks for me.

(Kind of ironic here how we're bringing in the risks of real-world mining to virtual mining.)

Here you go! LOL


http://www.newegg.com/Product/Product.aspx?Item=N82E16835706015


---------------------------------------------------


Bearing Type:
    Ball Bearings

RPM:
    5500 RPM

Air Flow:
    252.85 CFM

Noise Level:
    66.5 dBA

Power Connector:
    3 bare wire or 4-pin Rated Voltage : 12V Operating Voltage Range : 8 ~ 13.2V Rated Current: 4.80 amp Rated Input Power: 48W Air Pressure: 35.877 mm H²O

Color:
    Black

Compatibility:
    Case

Dimensions:
    120 x 120 x 38mm

And just let this sucker blow on the cards?

If the case is going to be closed (with this fan as a side intake), you'd need to improve outflow as well somewhere else in the case...

MOAR FANS. or open the case, and point a big fan into it.

Using two 12cm Fans, both lying right on top of the cards, blowing air into the gaps. I'm getting 56 - 74°C, all cards OC'ed from 800 to 950Mhz.

that looks insane, more pics please! :D

66.5 dBa?! You have any idea how much noise is it going to generate???

Atleast i do, Yes, 66.5 dBa ;D

In all seriousness tho:
http://www.gcaudio.com/resources/howtos/loudness.html
That is about as much as normal conversation.

Currently at my workstation the noise level is probably plenty above 66.5.

That wiring job just screams fire hazard.

You should space each card with some foam or random stuff you find :O
If you are using a case, take the side panel off and get a fan (those standing square ones are best) and blow straight at the cards. Lowered the temps on my 6990 by 15C.
If you are going caseless, put 120mm fans on top of the cards, and other standing fans around it. Go look at the mining rig pic thread for more reference.
Make sure the room the rigs are in has good airflow. I put mine next to the window.

Good luck!


A 6990 at max load is like 70-80 decibels. :O

 
+1 just put two or three fans right on top

I'm really not trying to spam anyone, and I encourage anyone to grab these anywhere they can find them, but the tiny risers (http://forum.bitcoin.org/index.php?topic=25492.0) I found make about a 6C difference by staggering the heights of the cards. By letting more air move around the cards, and letting some of them directly suck in more air by being higher than their neighbors, it works really well. It's harder to use if you're using a traditional case because the cards can't be screwed down then, but it made a big difference for me.

Less than a 6990. I measured 88.6dB at 100% fan speed, lol.

It literally sounds like a jet takeoff.