Dedicated PhysX GPU performance dependence on PCI-E bandwidth
Using a mid- or low-end GPU as dedicated PhysX card is quite popular idea today (even among ATI owners), while PCI-E bandwidth requirements for dedicated PhysX GPU are not absolutely clear. Everyone knows, that x8 and even x4 would be enough, but what about PCI-E x1 ?
PCPOP.com has published article today, that investigates PhysX performance of GTX295 + 9800GT setup, with 9800GT used in PCI-E x1/x4/x8 cases (unnecessary pins were taped).
And, surprisingly, even PCI-E x1 usage isn’t affecting performance as much as it should at a glimpse.
You can read rest of the article here
BTW, users with old mobos (or lack of free full scale PCI-E slots) are asking sometimes – “What if I just put my old 9600GT in PCI-E x1 slot ? Would that be enough for PhysX ?“. Now they have some clarity. Of course, mechanical “adjustment” will be needed to make it fit, that can result in GPU/mobo malfunction, so we don’t recommend even to think about it until you are clearly sure.
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.
Amyn (QUOTE)
Amyn
27 Jan 10 at 9:45 am
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.
Richard (QUOTE)
Richard
3 Mar 10 at 8:52 am
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.
Ron (QUOTE)
Ron
22 Apr 10 at 11:22 am
hi,
did all tests they performed on v1 pci-e or v2, cause in article x58 chipset have both standards from different x58 and ich10 hubs? i guess it was v2 but either assume it could be v1 from south bridge too.
[nv40] (QUOTE)
[nv40]
5 Aug 10 at 12:36 am
Am I susposed to read chinese now??
that link goes to a chinese language website.
jose (QUOTE)
jose
2 Sep 10 at 6:50 pm
jose
Am I susposed to read chinese now??
You don’t need to read – graphs are sayng more than enough
Zogrim (QUOTE)
Zogrim
3 Sep 10 at 12:46 am
nobody knows? :*
[nv40] (QUOTE)
[nv40]
5 Sep 10 at 12:23 pm
Luckily, Asus P5W64 has 4 full size PCIe slots with various lanes depending on config!!
Nice find!!! =) (i’m sold!)
ping2low (QUOTE)
ping2low
8 Oct 10 at 8:16 pm