Cross-fire a 6970 and 6990?

[tmptfate]

I am beefing up my rig with the addition of a 6990 and before buying the card I need to make sure I can cross-fire the 6970 that there currently. Has anyone done this combination or can tell if if it wont work? Thanks.

Oh and cooling is not a factor, the 6970 has a water block and I would be getting a 6990 water block as well (the whole system is water cooled, nice and quiet, mmmm)

[sojolly]

I am interested in your waterblock experience.  I have three 6870's running in two rigs, soon to be 7 rigs.  My case is very large and rackmountable so it has lots of room for extra stuff.

Anyone have temperature stats on before waterblocking versus after?

My 6870's are running at 84, 102, and 102degC at full load (air cooled with dual fans on the cards and maximum airflow, fans at auto).

Sojolly

[rainman]

First, you do not need GPU's to be running in Crossfire mode for the purpose of mining, just being present on your computer should be enough.

If you are wondering about Crossfire for those times when you aren't mining and want to run today's equivalent of Crysis (no clue what that might be) at max settings, then from my understanding Crossfire works between any GPUs as long as they are from the same generation, i.e. all cards hd 6000, or hd 5000.

The most cards I have personal experience with in Crossfire mode is 2 GPUs. I do not know for sure what the case would be for a 6990 plus another card, as the 6990 is already two GPU's in and of itself. I know you can Crossfire 3 cards together, but I have no idea about a 2 cards with a total of 3 GPUs.

I have heard of people crossfiring two 6990s together, so that leads me to think you can crossfire a 6990 with a single GPU card. Do some google searches, I bet this has come up before.

Three 6970 cores Crossfired together? What are you planning on doing with that power? What game or other app needs that much? Today, anyway.

[rainman]

@sojolly

102degC? That is pretty damn hot. Have you had any luck underclocking the memory on those cards? I think it would help alot if possible with your card, and bring the temps down to a safer zone. Safe in the sense of putting less wear and tear on the cards and giving them a longer lifespan chugging away at hashes.

[sojolly]

@sojolly

102degC? That is pretty damn hot. Have you had any luck underclocking the memory on those cards? I think it would help alot if possible with your card, and bring the temps down to a safer zone. Safe in the sense of putting less wear and tear on the cards and giving them a longer lifespan chugging away at hashes.

Just got the rig going on Friday.  Tried Linuxcoin first, was interesting but not sustainable longer term as i want the machines to be headless and autoboot to mining.

Finished configuring CENTOS last night and now looking into tuning.  I underclocked the memory on my windows7x64 rig and that 6870 runs at 96deg at full load in a not ideal case for airflow, so it helped a bit.  Will underclock the memory on the centos machines and report back the difference.

Sojolly

[tmptfate]

Thx everyone, I had read that as long as the GPU series was the same it should work but I wanted to get some feedback as well.

Three 6970 cores Crossfired together? What are you planning on doing with that power? What game or other app needs that much? Today, anyway.

I know some people who Bot a popular MMO and am debating getting a beefy system setup to rent out to them, so I figured beefing up my Bitcoin rig would be a good experiment for if I want to do that. I also just like seeing how far I can push a system in terms of power, hehe.

[tmptfate]

So I just realized, am I going to need to get a bigger power supply for my rig if I expand it like I described in my first post? I am currently using the Corsair TX-850W with the 6970 but dunno if that will be enough with a 6990 added in.

[shata]

Its expensive but I recommend 1kw or 1.2kw PC Power and Cooling.

I run nothing but PC Power n cooling in my rigs. Super reliable and 7yr warranty.

[snox]

850w will work, but it will be on the edge, i used a 1000w without straining it at all, only bronze 80+ aswell.