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Crossfire questions

MrMartyn1984

MrMartyn1984

MrMartyn1984

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Joined
26 Jun 2009
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200
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Hi all

I have found myself in a position with two XFX 6770's now my current board an M4a78 pro obviously can only take one.

I'm pretty new to gaming on pc's and understand I can put two of these together if I buy a new board. So I've been looking at an M5A88 V Evo, it's cheapish and has the Core Unlocket which might help my x2 550 and does crossfire, however it says PCi E x16 and then (x4 mode) what's this all about and will it affect performance?

I've now got a 750w psu so powers not a worry. Just wondering if I'll see the benefit of using crossfire?

Cheers

Martyn
 
The PCI-E's x-- mode shows you how many lanes of data the motherboard directs to the PCI-E slot. Each slot can take either x16, x8, x4 or x1. The x1 tends to be the little (1 inch) PCI-E slots that you physically can't fit a graphics card in so we'll ignore those.

When running two graphics cards, ideally both cards will run at their maximum 16 lanes each. If the motherboard architecture doesn't have that many to use, it may split them and run each card at 8 lanes each - known as x8/x8. In the case of the motherboard you're looking at, one card gets 16 lanes, one only get 4 (hence x16/x4). This will mean a hit on performance, probably about 10%-25% compared to a x16/x16 setup (source: http://www.tomshardware.co.uk/pci-e...ipset-gaming-performance,review-32164-10.html). Your hit may be less as the 6770 is less powerful than the 6950 they used in their test, but bear in mind at some point you will want to upgrade.

Best advice is to go for a motherboard that either runs x16/x16 or x8/x8 but I wouldn't recommend x16/x4 as it's too much of a performance hit.
 
Thanks for the info, makes a lot more sense. I'm kind of stuck as what to do as I like ASUS boards and would like to test this Corr Unlocker and as I've never seen two cards runnings I should still see a decent boost in performance from what you've said. Alternatively I could buy a different board and eventually a different CPU.

Whats the best cheap ASUS board I can get with 16x?
 
can't help you with a board but xfire is easy.

make sure you have a bridge, all plugs in and it should pick it up the next time you boot.

thats all you need to do......simples

jb
 
You need 2 x16 PCI-E slots to fit 2 cards and a CrossFire compatible motherboard.

The slots should ideally be electrically x16/x16 or x8/x8 as explained above.

Ideally you want a motherboard with enough space between the slots so that the cards aren't sandwiched together.

The bridge is just used to connect the cards for CrossFire and is usually supplied with the graphics cards.

You end up with something like this:

 
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Ok thanks. Well I've got 2 6770's new and boxed but no bridge supplied?

Will have to see what board I can buy and also buy a bridge.

Thanks for the help.
 
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