Is 4850 saturating the PCIE x8?

O

ofDoom

Weaksauce
Joined
Nov 23, 2005
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For some reason my mobo (Biostar I45) won't run my Palit HD4850 in x16 mode, so I have to turn Crossfire on to make it x8-x8 instead of x16-0. Am I taking a big hit on performance by running it in x8 mode?
 
x8 should not be an issue.... run 3dmarks and compare score against some reviews of the video card (try to find a review with a similar cpu to yours).
 
That's a PCIe 2.0 slot, so the fact is it delivers as much bandwidth as a PCIe 1.0 x16 slot. This will not be a problem for a 4850...you'd have to go 4870x2 for this to be a potential problem.
 
pci-e 1.0-1.1 can deliver a maximum rate of 2.5gb/s of data per pin. an 8x pci-e 1.1 can theoretically push 20gb/s of data. pci-e 2.0 can deliver 5.0gb/s of data per pin, so an 8x pci-e slot can theoretically push 40gb/s of data. i've not seen any examination that categorically affirms the claim that pci-e 2.0 is providing 5gb/s of bandwidth or anything close to it. as to the op's problem, if you get no display from the top most pci-e slot then, you should try to get a refund or exchange. i know of no feasible way to force the second pci-e slot to run at 16x.
 
I have a TP45HP...almost same board as the OP. Do you have your jumpers on the board set correctly?
 
I'm getting display from the first slot just fine. However, the board would power on and off 2 times before POSTing if jumpers are in the non-Crossfire position. It's supposedly related to the way BIOS applies new settings and not the card/faulty mobo. I'm not the only one having this problem, either.
 
I have two 4850's. One on 16x and on at 4x.

Kinda wondering about crossfire preformance with that second card PCI-E lane speed.
 
not good. expect very inconsistent frame rates. it was bad with 3850 512's, and 4850's are significantly more powerful cards.
 
I have my card running at X8 on the biostar tpower i45 and notice maybe 400 points diff on 3dmark at the same speeds. and no diff in games
 
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