How to keep 4x 6970 cool

[adam1230]

Hey guys,

I have a single board with 4x pci-e 16x slots in it. I have 4x 6970 cards. When I plug them all in there is literally zero room between them (they touch unless i put rubber spacers between them). My PSU is on the way so I havent been able to test them all together yet. My question is, will they not cool being so close together? The cards are the ones that have an interal fan that pulls air from the back of the GPU and pushes it to the front. Anyone have experience with this type of setup and know if they will stay cool enough for mining? I dont want to use risers if I dont have to. This is a breadbox (out of the case) setup btw.

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[fattypig]

Hey guys,

I have a single board with 4x pci-e 16x slots in it. I have 4x 6970 cards. When I plug them all in there is literally zero room between them (they touch unless i put rubber spacers between them). My PSU is on the way so I havent been able to test them all together yet. My question is, will they not cool being so close together? The cards are the ones that have an interal fan that pulls air from the back of the GPU and pushes it to the front. Anyone have experience with this type of setup and know if they will stay cool enough for mining? I dont want to use risers if I dont have to. This is a breadbox (out of the case) setup btw.

You can try removing the GPU case, then have a really strong intake and exhaust fan.

[Ritual]

May I ask what the objection is to risers?

Imo (which is ONLY an opinion), you'll fry something with that setup.

[adam1230]

May I ask what the objection is to risers?

Imo (which is ONLY an opinion), you'll fry something with that setup.

The only objection to the risers is that my setup is already mounted on wood and ready to go and I've never used risers before. I'm not sure how I would mount something on risers. I've seen pics but they all look custom and havent found any metal forms that would work out of the box.

[Ritual]

Well, being honest with you, I'm not sure about it myself. I won't get my hardware til then end of this month, so I'm still researching, but I decided within about 20 mins of reading about rigs that I couldn't get away without risers.

I still need to work out the exact ones I need for my board, but the basic premise is "Stick the skinny end into the board, stick the card in the fat end". If you go above 2 cards, I'd recommend powered risers for the others (risers which have a power molex that you can plug the PSU into) or you run the risk of drawing too much from your mobo and murdering it. I can't be any more specific because I haven't worked it out 100% myself yet.

But to boil it down to the basics, if you have 3 or 4 cards, running at 80C each, a millimeter or less apart, they are going to cook each other. The heat simply will not have enough time to get away from the cards before something gets melted.

There are some serious experts on these boards who can help you work out the specifics.

Oh, and wrt to mounting them....people have shown it can be done in a milkcrate, so that's just a small matter of messing with the container (not all people use PC cases ) until the cards are (a) away from the board a bit and (b) away from each other a bit and (c) sitting solidly on something. Alot of people seem to use the box the card came in

Rit

[ineedit]

May I ask what the objection is to risers?

Imo (which is ONLY an opinion), you'll fry something with that setup.

The only objection to the risers is that my setup is already mounted on wood and ready to go and I've never used risers before. I'm not sure how I would mount something on risers. I've seen pics but they all look custom and havent found any metal forms that would work out of the box.

Woods good 

But you really need to separate those cards apart by using risers. The basic rules are if the card is powered by a PCI-e then use a powered riser, if you can afford them then get the risers that connect using USB cables. If the card is on the list here https://bitcointalk.org/index.php?topic=36061.0 then use risers that have the switching built in, there should be a small capacitor at the fat end. You may be unlucky and get a motherboard that is not on the list but in that case just short A1 B17 and you will be away but add it to the list please.

[cdog]

My question is, will they not cool being so close together?

So you spent hundreds on GPUs not knowing how to set them up properly, just hoping it works?

It wont. You can probably run 2 cards without risers. Maybe if you had 280x's you could undervolt a ton and run 3-4 on a single mobo in a cold area with extra fans and have temps under 90c

[adam1230]

May I ask what the objection is to risers?

Imo (which is ONLY an opinion), you'll fry something with that setup.

The only objection to the risers is that my setup is already mounted on wood and ready to go and I've never used risers before. I'm not sure how I would mount something on risers. I've seen pics but they all look custom and havent found any metal forms that would work out of the box.

Woods good 

But you really need to separate those cards apart by using risers. The basic rules are if the card is powered by a PCI-e then use a powered riser, if you can afford them then get the risers that connect using USB cables. If the card is on the list here https://bitcointalk.org/index.php?topic=36061.0 then use risers that have the switching built in, there should be a small capacitor at the fat end. You may be unlucky and get a motherboard that is not on the list but in that case just short A1 B17 and you will be away but add it to the list please.

Thanks for the info man. I appreciate it.

My question is, will they not cool being so close together?

So you spent hundreds on GPUs not knowing how to set them up properly, just hoping it works?

It wont. You can probably run 2 cards without risers. Maybe if you had 280x's you could undervolt a ton and run 3-4 on a single mobo in a cold area with extra fans and have temps under 90c

No, I have 10 rigs right now running 2x GPUs but this is the only one that has 4x pci-e x16 slots. I've been running a 10 MH/s system for about a year but decided to try a 4x pci-e mobo since I got a great price for it. It takes all of 30 minutes to learn what you need to learn if you know where to look but I wanted to see if anyone here had any HELPFUL advice or experience instead of sarcasm or negative comments.

So since you obviously know more than me can you point me to a link for something that I dont have to custom build to mount the 2 cards on that I need risers for? (something that is not a milk crate).

[Wipeout2097]

It helps to run them as unlocked 6950's. That is, still with 1536 shaders but at 1.1V instead of 1.175V. You can still pull ~480 Kh/s out of them at core 880 and ram 1500

See this: http://www.techpowerup.com/rbe/ and http://www.techpowerup.com/articles/overclocking/vidcard/154

[gsupp]

So since you obviously know more than me can you point me to a link for something that I dont have to custom build to mount the 2 cards on that I need risers for? (something that is not a milk crate).

If you don't want to custom build it, you can check out "Large ATX Tray (mining tray)" at: http://richchomiczewski.wordpress.com/home/trays/

Although you said you currently have everything mounted on wood. Is that a custom wooden frame you built? If so, I think it could be modified or you could build one that gave more vertical space so you can use risers. Something like this:

[adam1230]

^ This may just work. The wood I am mounted on is just a square and I put plastic risers on it and mounted the mobo to it. Adding a couple small pieces of wood to it like this may do the trick (I ordered 2 risers today). Thanks for the feedback man.

[Bitweasil]

They should be fine.  Make sure you have good airflow in the proximity of the intakes and they'll stay cool.  Even the boxy cards are pretty good at sucking air.  You probably want to run the GPU fans at 80% or so.

If you're an open air setup, PCI-E slots have a good bit of "flex" built into their spec.  You can put a 5mm spacer between the cards to increase airflow to their fans without affecting the electrical connection and open up space for them to breathe.

I would suggest against using risers unless required, as they can cause reliability issues.  The're a possible solution, but I strongly discourage their use.  Try without them first.

Source: Extensive experience building dense, multi-GPU rigs for password cracking, including fairly reliable "impossible" systems such as 4x 6990s in a board without extender cables.

[crazyates]

They should be fine.

I would suggest against using risers unless required, as they can cause reliability issues.

Source: Extensive experience building dense, multi-GPU rigs for password cracking, including fairly reliable "impossible" systems such as 4x 6990s in a board without extender cables.

Password cracking must be different than LTC mining, because there's no way in hell you could run 4x 6990 for LTC mining while crammed into a case with no space between the cards. Not unless your ambient was like 0F, and you had some delta fans blowing air between the GPUs. The only 4x GPU rigs I've seen that are still in a case are watercooled.

I've run 3 GPUs crammed next to each other inside a nice gaming case with lots of airflow. You pretty much HAVE to undervolt, and run the fans on max, or else the middle/top cards will overheat. Also, blower fans work best in this situation, as they dump heat outside the case, not into it (and by "best", I mean "slightly less shitty").

Working with risers isn't that hard, esp if you get those new USB ones. They are more reliable, and are pretty flexible, so you can position the GPUs themselves wherever and however you want.

[adam1230]

Here is what I ended up doing:



It's not pretty but it gets the job done and nothing overheats. 1.75 MH/s