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Crossfiring a 7990 and a 7970

Footyslayer

Footyslayer

Footyslayer

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Joined
16 Mar 2009
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1,917
Hi all,

I am pondering getting the upcoming MSI HD 7990 and crossfiring it with my current Gigabyte 7970.

My motherboard only has one 1 x PCIe 3.0/2.0 x16 (blue) and one x PCIe 2.0 x16 (x4 mode, black). Would the crossfire work ok with only one pci 3.0?

Is my processor ok with this? Also would my PSU be powerful enough? All current specs are in my sig :)
 
As far as I'm aware, you'll lose at least 5% (maybe up to around 15%) by running two cards at X16 / X4.

I would say that you'll still see a massive and worthwhile boost, though there will be a few titles titles that would benefit more from a bit more performance (eg. 3770K).

I'm not sure about the psu, though I think it would be fairly close either way.

Hope this helps a little. :)
 
no, I would not do it myself.
x4 is a blockage and you might run into sync and such issues along the way.
if you play at 1920x1080 or such, well its not a good call IMO.
 
Thanks for the reply :)

I am in two minds wether to crossfire or just use the 7990 alone and sell the 7970.

The only things I would worry about with a crossfire is too much drain on my PSU and any potential bottleneck.

Obviously I'm still open to feedback on those concerns!
 
You don't really even need to OC the 7990. It's a stonking card as it is :) You've got a single board Xfire 7970 card...I'd doubt too many games will tax two 7970's to the max
 
If you have 1 7970 then wouldnt another be the sensible choice to crossfire with?
 
subbytna said:
You don't really even need to OC the 7990. It's a stonking card as it is :) You've got a single board Xfire 7970 card...I'd doubt too many games will tax two 7970's to the max
Click to expand...

los said:
If you have 1 7970 then wouldnt another be the sensible choice to crossfire with?
Click to expand...

Yeah I thought this earlier, two 7970's in crossfire.

However would I still have a problem with my motherboard only having one 1 x PCIe 3.0/2.0 x16 (blue) and one x PCIe 2.0 x16 (x4 mode, black)?

Also would any 7970 work or would it need to be two of the same make and model?
 
Footyslayer said:
Yeah I thought this earlier, two 7970's in crossfire.

However would I still have a problem with my motherboard only having one 1 x PCIe 3.0/2.0 x16 (blue) and one x PCIe 2.0 x16 (x4 mode, black)?

Also would any 7970 work or would it need to be two of the same make and model?
Click to expand...

The motherboard will work ok but you will take a hit on performance prob about 5-15%.
Any 7970 will work but best to get one with a decent cooler to keep it a bit cooler
 
Thanks for the excellent replies. I am going to crossfire the two 7970's :)

Last question, which 7970 to add to my current?

http://www.overclockers.co.uk/showproduct.php?prodid=GX-204-MS

or the same as my current but the GHZ version...

http://www.overclockers.co.uk/showproduct.php?prodid=GX-108-GI&groupid=701&catid=56&subcat=938

or

http://www.overclockers.co.uk/showproduct.php?prodid=GX-181-MS&groupid=701&catid=56&subcat=938

With quite a bit on price difference are the more expensive cards worth it for crossfire?
 
I hate to bump but I am looking to order today.

Can anyone recommend the best 7970 for me from either my options in my above post or another 7970 all together. The MSI at £260 does look appealing.
 
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Footyslayer said:
Hmmm,

I did read that 2 7970's would be faster than a single 7990 though, and cheaper.

I'm a tad confused now then :confused:
Click to expand...

If you have a mobo where you can run 2 7970s @PCI-E 2.0 or 3.0 x16 they will be faster, but your mobo does not support this which means putting a single HD 7990 in the x16 slot should give a little more performance.

Having said that the difference in performance will be small and probably something you will not notice.
 
Kaapstad said:
If you have a mobo where you can run 2 7970s @PCI-E 2.0 or 3.0 x16 they will be faster, but your mobo does not support this which means putting a single HD 7990 in the x16 slot should give a little more performance.

Having said that the difference in performance will be small and probably something you will not notice.
Click to expand...

Now that does make a lot of sense! I'll go for the 7990.

That is decided then, cheers :)

*Edit*

Just a quick query, the two PCIe'S ON my mobo are...

1*PCIe 3.0 x16 slot
1*PCIe 2.0 x16 (x4 mode, black)

Both say x16 but the secondary has the (x4 mode, black) added to the description, so which is it?

"It also caters to a wide range of end users by including features such as AMD Crossfire for the ultimate multi-GPU performance gaming platform."

https://www.overclockers.co.uk/showproduct.php?prodid=MB-555-AS
 
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