7970 DirectCU II Tri Fire Help

[erazorzedge]

I bought 3 7970 DirectCU II cards for use in tri fire; however, I'm getting the same performance with all 3 cards as I am with just two.

I'm running a 2600k @ 4.8GHz on a Maximus IV Extreme-Z board and 8GB RAM @ 1600MHz with a Corsair AX1200 PSU. I'm on 12.6 WHQL drivers currently. I've tried running each card in different slots, with one or all 3 monitors connected, and still no luck getting anymore performance.

One of the 3 cards shows a lot more information under GPU-z than the other two, such as amperage, wattage, VRM temp, etc. The other two only show VDDC, GPU diode temp, and memory usage. The card that shows more info also seems to be stuck at ~1.06V whether under load or idle, while the other two go from 0.85V at idle to 1.175V under load.

I'm thinking of RMA'ing the odd-card-out and seeing if a replacement will fix this. Can anybody offer any help with this?

[WhitePaw]

Wake the config up..

Activate the 3 way crossfire in Catalyst..

reeeeebooot

Now they should work all together in whatever tweak prog u using..

This is the type of "error" that is kinda hard to help u with, you see the symptoms, i dont...... dont give up..

[erazorzedge]

I've ran tri fire before with my 6970's and have never seen this type of problem. I've tried setting crossfire to only two cards and then back to three cards. I've ran several benchmarks such as 3dmark11, heaven, etc., and all of them give me the same "score" with two cards enabled as with three cards enabled. I can see the GPU usage is down to around 70% on the first card, while the 2nd and 3rd are around 90%. This does not change with the physical order I place them in on the board.

[HiVizMan]

Have a look in the manual and see what the lane allocations are when you run two or more VGA.

Single card PCie lane 1 will be 16x Dual card, or three cards it drops down to ?

[erazorzedge]

The #1 slot is a x16/x8 (x16 when only this slot is populated, x8 if any other slot is populated). The 2nd and 4th slots are x16 always. The 3rd slot is x8.

I run in slots 1, 2, and 4. The spacing between slots 1 and 2 is double wide, while between 2 & 3 and 3 & 4 is single wide. So I run at x8/x16/x16 which I thought might make a difference at first, but I took the 3rd card out an only tried with only 2 cards in slots 1 & 2 (x8/x16) and then again with slots 2 & 4 (x16/x16). The difference was negligible, if any, in benchmarks and actual games. So I don't think it's a PCIe lane issue.

[HiVizMan]

Yeah the advantages with tri Crossfire over dual is near zero by the way. That is just how it is. If you want the max out of your VGA multi cards you will need to go X79 for the full benefit but really it is not worth it.

[r3zn0r]

depending what u are doing or playing it may not b able to use all 3 cards. i.e. skyrim no. battlegield 3 yes.

[erazorzedge]

I'm sorry, but there is always a benefit in adding another card, especially when running 3x 1920x1200 screens. Even when running 3dmark at 1280x720 (or around there), I've always seen improvement when going from two cards to three. So how is it that you say the advantage with three cards is "near zero" over two? Granted, in my particular case, the advantage IS zero. I mainly play Battlefield 3 at 5760x1200 resolution and there is no noticeable frame rate increase when going from 2 cards to 3.

I was just searching google for the available amount of PCIe lanes with my setup and saw that the SB cpu's offere 16 lanes internally and at least 8 more via the Intel chipset, with the NF200 chipset throwing in some more lanes. Could it just be that every available lane is used up and tri-fire is not possible on my setup? Does anyone here have a Maximus Extreme-Z with a SB CPU and more than two video cards that can offer some insight?

[r3zn0r]

with those drivers and 3dmark11 my gpu usage is 100%/50%/50% so tri fire isnt working properly. but battefield should be. maybe the lanes are slowing it down but imo it shouldnt be that noticable. i got no more ideas sorry.

[erazorzedge]

What's your rig consist of?