What is a good enough dedicated Physx card?

[Slav2012]

Ok so Ive got my old rig outa the garage as i want to test it and have some fun with it. So specs are below

XFX nForce 780i SLI motherboard

Intel Core 2 Quad Q9400 2.66Ghz

Mushkin/Ocz 8GB DDR2 800mhz

Evga Gtx 285 superclocked Edition

Inno3D Gtx 285

Thermaltake Toughpower 750w modular psu

Ok now thats the stats or atleast what matters. My current Power needs are 595w on average with the current system. My motherboard has 3 way sli compatibility or i can just use the 3rd pcie slot to use a physx card while my gtx 285 run in sli.

So my question is what card is good enough for purely physx along side my sli gtx 285.

Now concider i have a 750w psu so this will barely sneak in but i can change the psu if i have to the main part is what is good enough as a physx card.

Would a 9800Gt or 9600Gt cut it? or maybe even a gts 450.

 

[marsey99]

96gt would do just physx but idk if it would just be better doing both on your current gpu as others have tested it in the past and adding a 2nd weaker card has been known to slow it down overall.

 

[KING_OF_SAND]

GT430

 

[Matthias2437]

Yeah a 9800 should be good. I had my GTX 9800+ in my gaming PC for a while with 2x GTX 570s and it some things I would get a slight performance increase. Not really that noticeable though.

 

[Techie103]

I would definitely lean towards the GTS 450 for physx.

 

[Rastalovich]

In an sli rig, a separate physx card should be slower.

 

[KING_OF_SAND]

In an sli rig, a separate physx card should be slower.

It's hit and miss.

 

[airdeano]

wasnt that kinda the thinking was to use an older card, until the appropriate card was located to complete the package?

usally i found that a bit-rate compromise was the "bottle-neck" jumping from a 192-380 bit-rate to a physx 32-128 actually

slowed the performance down. but consistant bit-rate (128 with other 128's) cards seemd to play well with each other.

airdeano

 

[equk]

I thought there were tests done that proved that having a slower 'dedicated' physx card actually hindered and bottlenecked the system?

*goes to find thread with video*

[media]http://www.youtube.com/watch?v=cbww3dhzK0M[/media]

if you go to 3:08 of the video u can see results

 

[Rastalovich]

Is what I thought, but I don't know if it was tested on something greater than 2x285.

If it were 2x470 or 480, I'd definitely say not to bother.

 

[KING_OF_SAND]

Well yea, it is just like any other part of your system. You have to treat you PhysX card as if it were a primary GPU in correlation to your system.

 

[BKCXb]

If you have a high end graphics card on 1155 you are better just letting it do PhsyX by itself

If your gonna add another card you are better adding another equal card and SLI them

Reason is a high end grapgics card will take a slight hit in performance dropping back from 16 lanes to 8 lanes when adding in the second card, if your gonna do that you want the second card to take more load off of the first one than it loses by droping down its lane count, and there is no better way than adding another equal card in SLI even if it only scales at 75%

If your running a lower down from the top card that isn't affected by the lane change you just need to add a card that takes the most load off the first without going overboard, too far up the line your back at adding in a second equal card for SLI