7970 Tri-Crossfire

[MikeGT2]

Hi,

MB: Asus Maximus IV Extreme (P67)
CHIP: 2600K @ 4.6 (on water)
GPU:
1: MSI 7970 Lightening
2: XFX 7970 Black Edition
3: XFX 7970 Black Edition
All on water

All the above are OC'd using After Burner...
CV: 1225
PL: +20%
CC: 1150Mhz
MC: 1575

I decided to test each of the 3 stages.. single, dual and tripple.

Here are my results...

Single:
P 9985
G: 9855
P: 11614
C: 8984

Dual:
P 16068
G: 19428
P: 11320
C: 9636

Tripple: (this is where it gets weird)
P 14841
G: 17324
P: 11304
C: 9247

I have the cards set up as per the motherboard manual recommended.
PCIE slots 1 (native), 2 NF200 & 4 (NF200)

Can anyone please advise why I'm seeing no improvements and actually a performance decrease in TRI-Crossfire?

(I've also tried the cards @ 1000Mhz which is stock for the XFX but the MSI's stock is 1070Mhz. Same result)

I have the extra power plug on the mobo for extra PCI-E power too.

thanks

EDIT:

I dug out a spare hard drive and decided to put a new install of windows 7 on it and test again to ensure there was nothing holding this back at the OS side.
Same results :|

 

[kilobravo]

What PSU do you use?

 

[tinytomlogan]

More cards doesnt always mean higher scores.

Dual is the max on your 1155 config, youve basically just wasted a lot of money

You should of been thinking CPU bandwidth and PCI express lanes. You dont really have enough of either

 

[MikeGT2]

What PSU do you use?

Corsair AX1200.

More cards doesnt always mean higher scores.

Dual is the max on your 1155 config, youve basically just wasted a lot of money

You should of been thinking CPU bandwidth and PCI express lanes. You dont really have enough of either

ok, thanks tom.
The 3rd card I got (MSI Lightening) was so I could play 120Hz Eyefinity on 3 display ports.

I'll prob disable the 3rd card for now. And then pull the rig apart and put the 3rd 7970 in my other rig which at the moment is missing a GPU (as I nicked the MSI Lightening out of it)

So x 2 7970 or 2 x 680 would be max for 1155?

 

[jamesriley94]

No - I think he means your 1155 personally. The Z77 platform with Ivybridge has PCIE 3.0 (not that it means much) but I'd guess that should give it a little extra juice for running a tri-fire set up. Although in gaming more than 2 makes no difference anyway