I've got 2 8800GTS cards in my PC and would like to use one of them as a PhysX PU.

It seems that because I have them set up for SLi I do not have the option to do this. Even by disabling the SLi option I still don't have this ability.

I'm guessing that the fact the machine supports SLi that this is why it isn't there.

If I remove the SLi bridge would that be all I need to do? Is there anything else I need to do to turn my machine into a PC with 2 independent cards?

Thanks

Well removing the SLI bridge is a definite requirement to have two independent cards! I would try that and see if it does the job first.

What drivers & board?

It's an Asus PN32 SLI Plus (IIRC) board.
The cards are GeForce 8800GTS 320Mb cards with the latest (188.something) drivers.

I removed the SLi bridge but I seemed to still be able to select the "Enable SLi" option and I stil didn't have the ability to select a dedicated GPU for PhysX.

I'll have a check of the BIOS tonight to see if there is a switch to turn off Sli.

I also found somewhere that mentioned a Vista bug that required a dummy monitor in the second GPU to enable to option in the control panel?!

Quite possibly, I use dummy plugs on all my vista folding rigs

I'm not sure why you would want to ditch SLi in favour of using one card for Physx. I used to run 2 8800GT's in SLi and had Physx enabled on both of them and I didn't take any sort of hit in perormance. By using one card for purely physx I can see you taking a hit in performance.

For what ever reason I couldn't enable physx until I download and insalled the following from Nvidia. I though it was all built in these days but it didnt work until I installed it. (and yet with the 185.85 drivers I'm using on Win 7 it is part of the driver!!!)

Physx System software

I'm trying to run it on Mirror's Edge and with SLi enabled I can play on high settings at 1680x1050 with no problems (highest settings causes slow down after a 15 or so mins, I'm guessing temperature based problems).

If I disable SLi and run at the same settings it works for 15 or so mins but then will crash (this is the same with Crysis and other games when not using SLi) "Mirror's Edge has stopped working" error message pop up.

However, with Mirror's Edge, if I enable SLi and PhysX and turn on PhysX in the game options it will play perfectly and look amazing for about 15 mins and then it will just stop. No errors the game just stops moving. The only way to get out of this is CTRL-ALT-DEL. I have even turned the setting down to medium and lowever the resolution to 13xx by 7xx (or something) but it still stops working.

I was trying to set up the dedicated card thing to try and overcome this problem.

What single card (reasonable price) can I buy now that will out perform 2 8800GTS 320MB cards in SLi? I may stick one of them in instead.

Cheap 4870?

Regards

Spreadie

Will that work ok with my Mobo?

IIRC the card I have is covered with NVidia stuff (ie BIOS settings all have NVidia on them etc...)

Will this mean I can't run the ATi card? I've lost touch recently on component type stuff.

You'll be able to run the ATi card on the board without any problems, you just won't be able to add a second and CrossFire them. I may be wrong, but could you not keep one of the NVidia cards in the machine and use that for physics, and the ATi card for the pixel pushing?

Can't mix nvidia & Ati in Vista

That's what I wanted to do but I'd need to get an NVidia (like Saspro said) in order to be able to do that.

Any NVidia cards similar to the 4870HD?

The 9800s seems a little under powered compared to it. What's the latest NVidia stuff?

How about this... CLICKY!

It's a close match between this and the ATi according to gpureview.com... CLICKY

Will the fact that my Mobo is PCI-E 1 not PCI-E 2 make a difference?

What sized screen & GPU?
Any budget?

The gtx260 is a bargain at the moment and is rather good

Scan have 216 stream GTX260s for a little over £120.

Just for balance, they also list this from ATI.