Crossfire question (matching cards up)

[Jeff1961]

I read somewhere recently that it is best if one can use identical gpu's with crossfire.
Not being very knowledeable, and often taking things too seriously...I was concerned that these two might not be a good match:

The one I have:
SAPPHIRE HD 6970 2GB GDDR5 PCIE

The one i'm looking at buying:
Buy the VisionTek Radeon HD 6970 2GB GDDR5 Video Card at TigerDirect.ca


I see this one...which "looks" almost identical to mine...and cheaper than the other one, but in another city:
Sapphire Radeon HD6970 2GB DDR5 *full* SAPPHIRE HD 6970 2GB GDDR5 | Pcsdesign.ca Canada [VC-SA-11187-03-40R]


Thanks. :)

[ShinraCorp]

Normally when pairing up two cards it's best if you can get 2 of the exact same thing.

Reason being is that each manufacturer has a different way to produce the card, one will be better cooled, the other better power consumption etc...

If you absolutely cannot find the exact same card you purchased, then you have to go with the one that has the exact same GPU in it, I do not know if you need the same amount of VRAM though. However you will have the risk of having big problems when you do not have 2 identical cards, like say frame rates dropping, artifacts, video corruption etc...

[Soullessone21]

I have done mixed crossfire before with very little issues as long as they are the same gpu family 69xx 68xx 67xx so on. Its nice to get the same but when all else fails try to get close to the same specs.

I crossfired my 6970 2gb DCII with a sapphire just like yours with little to no issues out of the norm.

[Jeff1961]

Thanks guys.

I noticed on the Sapphire page...there were a lot of different 6970's. With some it's obvious that they are an overclocked version, but many seem identical. In those cases, I would think they are identical...but i'm not sure why they have those listed differently. The specs on those pages are identical.
I'm not sure if this link will work...but it shows the 3 cards i'm talking about in a comparison on their page. Three different cases, exact same specs. One has a fan in the middle, the other two at the end...and one of those says pcie.
Sapphire Product Comparison

Perhaps its just a marketing ploy. lol
Maybe it's a way of indicating different batches they made? Slightly different gpu chips?

Anyways...i'm tempted to buy the one in Hamilton then. It looks exactly as mine is. It's cheaper. I'm sure I can get it delivered in a way that is safe. And i'll contact them first to make sure it is the exact one their photo is showing.

Thanks again. :)

...should have known that link would not work, here's a screenshot:

[Dzzope]

The first has a custom cooler and the others are probably different revisions of their reference design.

[Masteroderus]

any 6970 should crossfire with another 6970. Even if they have mismatched memory sizes. Even if they have mismatched clocks. I have tested with a dcuII and a toxic 6950. It even worked when one was modded to unlock shaders and the other wasn't.

[Dragonstongue]

as long as they are from the same family like mentioned x9xx x8xx x7xx etc they will "mix" however, just like using ram, it is by far betetr to match the original speeds/capacity to get the most from it, I would also stay away from visiontek with a 10ft pole, unless they have majorly changed thier ethic for dealing with customers RMA and the like, there are better choices, even if they cost $10 more.

[cul8erppl]

question along this topic...i know someone asked this before, but i'm too lazy to search...what happens if i crossfire two of the same series cards, but memory sizes are different?...for example, radeon 7850 2gb version in my PCIE @ x16 mode & radeon 7850 1gb version in my PCIE @ x4 mode?...will it downscale and run both cards on 1gb of memory?...not sure how the different memory sizes will affect performance...i guess the same question also for GPU speeds, like if one was OC'd and the other wasn't...

[IRQ Conflict]

Lowest common denominator. That's how it works. 1 card has less ram/speed it will drag the other down with it.

[cul8erppl]

^^^ yeah, that's what i thought...thx dude!