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PCIe 2.0 x8 enough for a pair of hd4850s?

Last response: in Graphics & Displays
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July 10, 2008 2:16:46 PM

does anyone know the difference in performance between two hd4850 @ X8 and two hd4850 @ X16?
is X8 enough? or will i need X16 to fully use the power of the two cards combined?

More about : pcie pair hd4850s

July 10, 2008 2:27:49 PM

Can't say for sure, but I do remember seeing a Tom's article that the difference between x8 and x16 for PCI-E 1.0 on most cards showed little difference. I'd say that even with the advancement in cards, x8 vs x16 on PCI-E 2.0 would also produce little difference, especially since 2.0 has doubled bandwidth over 1.0, meaning 2.0's x8 is 1.0's x16.
July 10, 2008 2:28:58 PM

8x will bottleneck the cards.
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a b U Graphics card
July 10, 2008 2:55:57 PM

it will bottleneck it but slightly u wont lose that much performance.
July 10, 2008 3:01:34 PM

ovaltineplease said:
8x will bottleneck the cards.

Since i have a DFI icfx3200 i would be very interested in more information regarding that bottleneck. Do you have any articles or reviews you base that statement on or is it personal experience?
a b U Graphics card
July 10, 2008 3:13:08 PM

http://www.tweaktown.com/articles/1472/intel_p45_vs_x48...

Tweaktown did a recent test between the P45 and X48 with 4850s and found that the 8x/8x was slower, by varying degrees, than the 16x/16x. Now, I take everything tweaktown says with a grain of salt, they aren't a great review site, but the test looked pretty well done. Check it out and see if the performance hit 8x gives is acceptable for you.
July 10, 2008 3:42:25 PM

nvalhalla said:
http://www.tweaktown.com/articles/1472/intel_p45_vs_x48...

Tweaktown did a recent test between the P45 and X48 with 4850s and found that the 8x/8x was slower, by varying degrees, than the 16x/16x. Now, I take everything tweaktown says with a grain of salt, they aren't a great review site, but the test looked pretty well done. Check it out and see if the performance hit 8x gives is acceptable for you.

Very interesting. Thanks for posting it.

a c 169 U Graphics card
July 11, 2008 7:34:15 AM

http://www.tomshardware.co.uk/forum/245454-15-crossfire...

Dual 8x is a very good configuration too,it doesnt have alot of difference with Dual 16x and its cheaper too.
Chipests like Nvidia 750i SLI, Nvidia 650i SLI,NVIDIA 570i SLI, NVIDIA nForce4 SLI, ATI Radeon Xpress 200, Intel 975x and ONLY 2 Intel P35 boards(ASUS BLITZ FORMULA and ASUS BLITZ EXTREME) support Multi-GPU at dual 8x mode.

Nvidia 680i (Dual 16x) vs Nvidia 650i SLI(Dual 8x)
http://www.techspot.com/review/45-nvidia-nforce-650i-sl...
July 11, 2008 10:43:52 AM

8x will bottleneck them in a few games at high resolutions. Games like Crysis and Flight Simulator X, at resolutions 1920x1200 and above. Crysis gets bottlenecked a bit even at 1280x1024, so that might be a good indicator of how 8x is going to fare in the future when more demanding games come out.

But for almost all the games out right now, they won't be bottlenecked much if at all. You could run them on 8x then upgrade the motherboard in 6 months.
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