5870 + 5970 in SLI... How Do I connect them?

[retro_party]

I've got a 3 way sli board that can connect 6 GPUS together.. How can I connect a dual GPU card with a single GPU card? Might be a newb question but I can't find the answer anywhere! Thanks

 

[hunter315]

Lets start slow here.

1. If you have a 5870 and a 5970 working together they are in crossfire not SLI

2. A 3 way SLI board can only support 4 GPUs, same way a 4 way SLI/CF board can still only support 4 GPUs due to the driver limitations.

3. Assuming your board supports crossfire along with SLI you just need a crossfire bridge, and need to enable crossfire in catalyst control center.

 

[retro_party]

Ok. thank you. Then my problem is something else then. When I get into a game (loading or right after) my PC freezes.. Im using 10.10e catalyst drivers.. =S All my windows updates are done.. Im trying to reinstall directx 11 now see what it does.. Do you have any suggestions? (I tried with the 5970 alone, game freezes still) I was using just a 5870 before.
I appreciate all your help, im not so good with all this.

 

[hunter315]

What are the specs of the rest of your system? Include the make and model of the power supply, since a 5970 and a 5870 together will draw quite a bit of power.

 

[retro_party]

Ok, I've fixed the crossfire problem. Now another problem comes up.. When I overclock the 5970 to 5870 clock speeds/memory games don't load and my PC freezes. But my system is stable with clock speeds on both cards.. I would really like to clock the 5970 to the 5870 speeds as this I think will have a major improvement in benchmarking..

My system is a core i7 920 stock speed.(Can't get my system stable with OC speeds yet)
6 Gigs Of OCZ memory
120 gigs SSD/600 GiG HDD
Asus P6T Motherboard
750 watt Corsair PS..(<-- Might be the problem) But I don't see why it would be so stable at stock speeds and unable to play/freeze when loading a game!)

 

[hunter315]

You say they are stable with those clock speeds on both cards, how do you know they are stable? When they arent doing anything intensive they drop down to 2D clocks and their power usage is minimal. Try running furmark on them to see if it freezes.

Upping a 5970 to 5870 speeds isnt going to help a ton, you already have plenty of graphics power for most things on high settings, it will only give you a few extra points in benchmarks, not worth it if it makes your system unstable.

 

[azzaparty]

im about to buy a 5870 to go with my 5970 so im doin some research.

the 5970s memory clock is whats wrong. seem like we will have to run the memory lower on the 5870 to match the 5970 unless we edit the bios and voltages

coz ur a noob just download MSI afterburner, set all 3 cores to 850mhz and all memory to 1000mhz and the problem should go away. good luck