Comments on: Dedicated PhysX GPU performance dependence on PCI-E bandwidth

By: Ron

Ron — Thu, 22 Apr 2010 08:22:44 +0000

I tried a similar test using a asus p5n 570i (pci-e v1 switchable x1 or x8) and msi 750i (pci-e v2 x8) with an e5200, ATI 4830 and NV 8800gs.

Generally speaking, my experience mirrors the article. However, the v1×1 did have noticeable, but tolerable, bandwidth issues. Both x8 slots were essentially equal however v2×8 was more fluid, I believe this is due to the halved latency of v2 and not the doubled bandwidth. Increasing the pci-e v1 bus to 111MHz reduced the lag on the v1×8 and noticeably boosted the v1×1 slot performance.

My guestimation is that a v2×1 or better would fully satisfy any physx needs. Unfortunately, Intel chip sets typically have pci-e v1 x1 slots and even worse, they are on the south ICH bridge which introduces even more latency compared to most NV and AMD chips.

By: Richard

Richard — Wed, 03 Mar 2010 05:52:51 +0000

I just bought a PCI Geforce 8400GS 512MB how bad of a performance hit would I have if I use a PCI card rather than PCI-E. My machine is an HTPC so the x1 PCI-e is being used by a TV Tuner. Any help would be appreciated.

By: Amyn

Amyn — Wed, 27 Jan 2010 06:45:39 +0000

Thanks this helped answer my question:

I have a Gigabyte extreme x58
Two 16x pcie
one 8x pcie
In order to give my 285gtx breathing room, I have my 8800gt in the bottom 8x slot.
How much of a performance hit does 8x physx have over 16x physx?

So, again thanks for the answer.
I kept it in 8x the heat generated by the two gfx cards in such close proximity isn’t worth it, especially cause I can just oc the 285 with the lower temps.