Quickie re: Xfire & Eyefinity

[Theophany]

Hi guys, just a quickie as the general misinformation, illiteracy and inherent untrustworthiness of some sites on the Internet is giving me a flipping headache.

I'm running a HIS 5850 (CoD:MW2 edition) on a Gigabyte GA-880GA-UD3H (rev. 2.1) and considering a move to Crossfire and Eyefinity as I've been offered a good deal on a Sapphire 5850 and (what would be my third) monitor and I'm trying to make my mind up as to pulling the trigger on the deal.

1. One monitor will require the use of an active DP <-> DVI adapter for Eyefinity, correct? Passive adapters do not work if what I have read is correct.

2. My mobo supports Hybrid Crossfire, which is no good to me. It has a 16x PCI-e and a 4x PCI-e slot; obviously the card on the 4x slot will run at a slower bus speed, but is there any reason that Catalyst drivers will reject cards on different speed PCI-e slots? Does the fact that the board is certified as Hybrid Crossfire rather than Crossfire mean that it simply will not work?

3. Once all monitors are hooked up to the primary card (one of which using DP, others on DVI) setting up Eyefinity should be as simple as opening CCC and enabling it through the Eyefinity menu, right?

4. Should all monitors be hooked up to the primary card?

Sorry if this is basic stuff, but I want to be sure of the answer and random forums that have come up in Google results are full of conflicting answers and posters telling each other that they're wrong.

Cheers!

 

[Final8y]

1) Passive adapters sometimes work & sometimes don't.

3) yes

4) yes.

 

[Theophany]

Given that Sapphire's active adapters can be had for around £15, I'd rather take the guaranteed solution - small price to pay to avoid the hassle and cost of returning.

Just need to know if I have anything to worry about re: different PCI-e slot speeds now. The motherboard manual has no references to anything but Hybrid Crossfire, which is no good, and the only info I can find on the 'net comes from a Russian source. I'm not sure I trust their poor English and the fact that the probably get a different end product to UK customers (Gigabyte distinguishes between EMEA and Russia I believe).

 

[deanpm]

Hi,

I hope I've not misunderstood your question about combining cards on the PCIE x16 and PCIE x4 slots.

I'm using the ASUS P8P67M-PRO mobo and two AMD 6950 cards with the first in the x16 slot and the second in the x4 slot. My mobo has two x16 slots, but I've separated the cards in order to lower the temps. With both installed in the adjacent x16 slots, there is pretty much no physical gap between the two cards which impedes air flow and is causing the first card to run very hot (94 degrees under 100% loading).

When I moved the second GPU into the x4 slot, Crossfire did not register. Turns out that slot was configured in the BIOS for x1 operation, not x4. Once I changed that, Crossfire sprang into life. There is of course a performance penalty. Based on some limited benchmarking, on my system, this equates to a 7 to 10% drop in performance.

Incidentally, the primary card still runs very hot in this setup (~90 to 91 degrees) under load and the fan spinning at ~50% which is generating far more noise than I'd like but that's a different matter...

Regards,

 

[DJ_Hughesy]

Hi,

I hope I've not misunderstood your question about combining cards on the PCIE x16 and PCIE x4 slots.

I'm using the ASUS P8P67M-PRO mobo and two AMD 6950 cards with the first in the x16 slot and the second in the x4 slot. My mobo has two x16 slots, but I've separated the cards in order to lower the temps. With both installed in the adjacent x16 slots, there is pretty much no physical gap between the two cards which impedes air flow and is causing the first card to run very hot (94 degrees under 100% loading).

When I moved the second GPU into the x4 slot, Crossfire did not register. Turns out that slot was configured in the BIOS for x1 operation, not x4. Once I changed that, Crossfire sprang into life. There is of course a performance penalty. Based on some limited benchmarking, on my system, this equates to a 7 to 10% drop in performance.

Incidentally, the primary card still runs very hot in this setup (~90 to 91 degrees) under load and the fan spinning at ~50% which is generating far more noise than I'd like but that's a different matter...

Regards,

that drop in performance is dependent on resolution if i believe... and at any "normal" res it shouldnt be that great of a diference to be worried about

iirc anything upto 2500*w/e x4/x4 works just as well as x16/x16 xfire

x16/x4 should be any diferent should it?

 

[deanpm]

that drop in performance is dependent on resolution if i believe... and at any "normal" res it shouldnt be that great of a diference to be worried about

iirc anything upto 2500*w/e x4/x4 works just as well as x16/x16 xfire

x16/x4 should be any diferent should it?

Ah! Excellent point. I should have mentioned that I've run all my benchmarks in 1920x1080. Am I right in thinking that the higher the resolution, the more pronounced the effect of using the lower speed bus?

Regards,