crossfiring limitations?

Thekwango

Thekwango

Thekwango

Soldato
Joined
5 Feb 2009
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N. Ireland
sorry about this folks, i know i've been banging on about this for ages and asking pretty much the same question after question. but i've goggled till i'm blue in the face and still not much more informed :o......so here it is again......

if i add a 2nd 5770 in crossfire my motherboard will only run it at 4x (i think) as opposed to 16x on the first. so am i correct in saying then that the 2nd 5770 will only be running at a quarter of its capabilites?

as such can any1 tell me what the real world improvements in fps etc would be. or more importantly would there be any point spending the money on a 2nd 5770. would i end up seeing next to no improvements?

i'm so confused that i'm strongly toying with the idea of grabbing a different board, possibly this one on sale

http://www.overclockers.co.uk/showproduct.php?prodid=MB-203-GI&groupid=701&catid=5&subcat=

this should run both gfx cards at their full potential, (again i think!!)

any advice greatly appreciated. i'm going insane here!! bought my rig to play games but since i've built it i've done next to nothing other than torture everyone on the forums and test my own sanity!! :p

am i being
 
According to the manual if you run crossfire then...

The PCIEX4 slot will run at 4x. Not much choice there as that's what it is wired at.

The PCIEX16 will also run at 4x! Presumably the cards need a matching number of lanes for crossfire to work. I'd guess that it would also drop to PCI-E 1.0 speeds to match the PCIEX4 slot.

I've no idea how well crossfire will work on 4x + 4x but it doesn't sound ideal.

The board you have linked to would allow both cards to run a 8x in crossfire (@ PCI-E 2.0 speeds).

If you compare the system block diagrams in the manuals you should be able to see the reason why. Look for the ‘switch’ (or lack of) on the PCI-E bus coming directly from the cpu.
 
4x + 4x!!!!! i take it that means i'd be better off just running a single card at 16x presumably? new motherboard me thinks :mad:

cheers anyway
 
You may want someone with the same board to confirm the 4x + 4x thing.

I was working purely from the manual. Page 12 has the following notes...

(Note 2) For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
(Note 3) When the PCIEX1_2 slot is populated with an expansion card, the PCIEX4 slot will operate at up to x1 mode.
(Note 4) The PCIEX16 slot operates at up to x4 mode when ATI CrossFireX is enabled.
 
(Note 4) The PCIEX16 slot operates at up to x4 mode when ATI CrossFireX is enabled
Click to expand...
.

yea was reading that too. just sent a quick note to gigabyte asking them to confirm. but i'm pretty sure you're right. ah well just one of lifes little lessons i guess!

but, thanks very much for your help/advice mate
 
That link says the Gigabyte motherboard you've chosen will be perfect to run crossfire/sli in, so it'll be fine.
Also running in x4 x4 usually halves the performance, which is quite painful when gaming. x8 x8 is enough, even for the latest cards.
 
That link says the Gigabyte motherboard you've chosen will be perfect to run crossfire/sli in, so it'll be fine
Click to expand...

the motherbord will run crossfire- yes - but at rather restricted levels. as the article in CAT-THE-FIFTHS post says "Warning: These P55 motherboards will cripple your Crossfire/SLI performance"

p.s. cool name CAT. how you come up with that??
 
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