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Dedicated PhysX GPU performance dependence on PCI-E bandwidth

with 8 comments

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).

pci-e_adj

And, surprisingly, even PCI-E x1 usage isn’t affecting performance as much as it should at a glimpse.

batman-physx-pci-e
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.

Written by Zogrim

November 23rd, 2009 at 10:31 am

Posted in Articles, Reviews

Tagged with ,

8 Responses to 'Dedicated PhysX GPU performance dependence on PCI-E bandwidth'

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  1. 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

    27 Jan 10 at 9:45 am

  2. 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

    3 Mar 10 at 8:52 am

  3. 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

    22 Apr 10 at 11:22 am

  4. 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]

    5 Aug 10 at 12:36 am

  5. Am I susposed to read chinese now??

    that link goes to a chinese language website.

      

    jose

    2 Sep 10 at 6:50 pm

  6. jose
    Am I susposed to read chinese now??
    You don’t need to read – graphs are sayng more than enough

      

    Zogrim

    3 Sep 10 at 12:46 am

  7. nobody knows? :*

      

    [nv40]

    5 Sep 10 at 12:23 pm

  8. Luckily, Asus P5W64 has 4 full size PCIe slots with various lanes depending on config!!

    Nice find!!! =) (i’m sold!)

      

    ping2low

    8 Oct 10 at 8:16 pm


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