PCIE x 16 and x 4 vs PCIE x 8 x 8

[David21]

im wondering if i crossfired 6850's if a pcie x 16 and x 4 is a huge bottleneck from pcie x 8 x 8
also is it possible to crossfire a 6870 and a 6850.

system specs
ati 6850
corsair tx 650
kingmax 8gb ddr3 1333mhz
intel i5 2500k

also is there much of a performance boost from 1333mhz ram and 1600mhz

cheers for any help.

 

[b1gapl]

I've read that the x4 does cause a bottleneck when you're CF is x16x4 compared to x8x8. I've also seen some benchmarks and x8x8 is usually 3-5% better. If it's worrying you that much it's mostly suggested to go for a motherboard that supports at least x8x8 CF.

Yes, it's possible to CF a 6870 and 6850. As long as it's in the same series.

There is no noticeable performance boost between RAM speeds of 1333 and 1600. It's only noticeable in benchmarks and not real world applications unless you're using software that is memory specific/intensive.

 

[patonb]

Wow all my thoughts on x4 have beenwrong..

Here a good read
HARDOCP - GTX 480 SLI x16/x16 vs. x4/x4 - GTX 480 SLI PCIe Bandwidth Perf. - x16/x16 vs. x4/x4

 

[b1gapl]

Did not expect that. I guess now it would depend if the PCIE slot was 1.1x or 2.0

Still not a noticeable difference if there is any.

How 'bout a x1/x1 comparison?

 

[Card Trick]

I did find this if anyone is interested.
AMD Radeon HD 5870 PCI-Express Scaling Review - Page 25/26 | techPowerUp

 

[David21]

okay thankyou for your feedback, i was thinking about getting either one of these motherboards.

MSY Online

or MSY Online

 

[patonb]

If you ever plan on getting 2 cards, the 2nd board is your best option.