[Warden]

So im running 2 GTX 460's sli on a Asus p8p67 pro mobo. Will i benefit if i put a xfx Alpha dog edition 8800GT in my third pci express slot and dedicate it to physx? Im currently playing Homefront wich utilizes physx. Thanks for the help

~Wardy~

 

[Defoler]

Yes you might benefit from it.

Just don't forget that the lower the card you get, the less the FPS gain will be.
For 460s SLI it might be ok, but I don't think the benefit will be high enough that its worth losing the bandwidth of x8/x8 to around the x4 as all the lanes are shared.

 

[staryoshi]

It wouldn't be worth it IMO because it'll cause your bottom card to run significantly warmer and louder. Just set physX processing to GPU2 - I've noticed performance gains when using GPU2 instead of GPU1 for processing physX in a SLI configuration.

Quote:

Originally Posted by Defoler Yes you might benefit from it. Just don't forget that the lower the card you get, the less the FPS gain will be. For 460s SLI it might be ok, but I don't think the benefit will be high enough that its worth losing the bandwidth of x8/x8 to around the x4 as all the lanes are shared.

Correct me if I'm wrong, but I believe the 4x 3rd PCIE lane is governed by the chipset, which wouldn't have an effect on the 16 lanes provided by the CPU.

 

[Defoler]

Quote:

Originally Posted by staryoshi Correct me if I'm wrong, but I believe the 4x 3rd PCIE lane is governed by the chipset, which wouldn't have an effect on the 16 lanes provided by the CPU.

If you read the motherboard specs, you will see that PCIE16_3 shares the lanes with 1 and 2, and USB port and some others.
Meaning that if you slap on it another card, you will affect the bandwidth of the other slots, and it will drop to 1x on the expense of other slots.

Quote:

Just set physX processing to GPU2 - I've noticed performance gains when using GPU2 instead of GPU1 for processing physX in a SLI configuration.

There is no real gain. FPS will be the same.
Its usually just telling yourself its better

 

[staryoshi]

Quote:

Originally Posted by Defoler If you read the motherboard specs, you will see that PCIE16_3 shares the lanes with 1 and 2, and USB port and some others. Meaning that if you slap on it another card, you will affect the bandwidth of the other slots, and it will drop to 1x on the expense of other slots. There is no real gain. FPS will be the same. Its usually just telling yourself its better

There was a tangible FPS increase when I tested physx-supporting games. The difference was several frames (single digit, but noticeable)

The chipset also provides the pcie lanes for the 1x slots as well as the eSATA/USB controllers. That is what it refers to. The primary 16/8x slots should be unaffected if my understanding is accurate.

Quote:

*The PCIe x16_3 slot shares bandwidth with PCIe x1_1 slot, PCIe x1_2 slot, USB3_34 and ESATA12. The PCIe x16_3 runs at x1 mode by default for system resource optimization.(PCIe x1_2 will be disabled.)

 

[AliceInChains]

yea that 4x slot doesnt affect your main pcie lanes. they will stay at 16x/0x or 8x/8x no matter what. just like it was with the p55 chipset its the same for p67.

 

[Villosa]

Sure if the 8800GT is free, then it wouldn't hurt to try it. If not then I'd forget about it. My belief is that any SLI GTX 400 or GTX 500 combo + PhysX is a waste if extra $$ is involved.

 

[windfire]

Quote:

Originally Posted by Warden So im running 2 GTX 460's sli on a Asus p8p67 pro mobo. Will i benefit if i put a xfx Alpha dog edition 8800GT in my third pci express slot and dedicate it to physx? Im currently playing Homefront wich utilizes physx. Thanks for the help ~Wardy~

Here is a member who has the same motherboard and CPU as yours and he has just tested his GTX470 SLI with 9800GT as Physx card:
http://www.overclock.net/nvidia/9884...x-470-gtx.html

According to his result on Mafia II, I think the gain is quite good. As his GTX470 SLI is not slowed down (but with framerate improvement), your GTX460s should not be slowed down (even though your resolution is slightly lower than his 1920x1080). And, your 8800GT has the same number of shaders (ie 112) as a 9800GT.

Granted that this is just a one-game test only. And that game Mafia II is fairly loaded with Physx effects. And I have not played Homefront yet and so I do not know the intensity of Physx in that game. Anyway, keep an eye on his upcoming testing of Metro 2033.

In general, you will see framerate gain with your 8800GT as Physx card.

 

[Warden]

Thanks for all the replies, yeah its a free card my friend had lying around so I'll install it tomorrow and test it in-game and let you know what i come up with. thanks again
~Wardy~

 

[Warden]

Thank you windfire for your reply and the link, very interesting. I didnt see it until i just posted. i will post my results tomorrow, TY
~Wardy~

 

[staryoshi]

Good games to test PhysX performance (That include built-in benchmarks, too) offhand would be:
Batman: Arkham Asylum
Mafia II
Metro 2033

There are others, but those are my go-tos. Batman: AA displays the best scaling with dedicated physx processing from my experience.

Attached are my physx testing results using a dedicated (overclocked) GTX470 for Batman: AA and Mafia II.

 

[Blacklac]

Unless a recent patched changed things, Homefront doesn't use PhysX even though it has the logo. Atleast in Multiplayer. I installed a PhysX card and verified it was running correctly. I never got usage on it while playing Homefront.