Have som software and hardware questions I want to clear out. All details is in my profil but heres the 2 relevante ones:
MB: ASUS Sabertooth X58 s1366
GPU: TWO MSI N460GTX HAWK 1GB GDDR5 in 2x16x SLI mode
Is wondering if insert a third GPU and dedicate that to PhysX is possible and if that choice would generate more data/graphic raw power advantage than what that would slow down the graphic system in form of bus speed? My MB supports 2x16x SLI and/or 2x16x or 2x8x1 Crossfire. It has 3 PCIe x16 slots, when using slot number 2 the bus speed of slot number 3 automaticly slows down to x1 in Crossfire mode (dont support 3-channel SLI).
Question # 1: Is it even possible to install a third NVIDIA GPU in slot 3 when running 2-channel SLI?
Question # 2: If that is possible, would the bus speed go down to 2x8x SLI + 1x PCIe PhysX dedicated NVIDIA GPU (slot 1 & 2 bus speed is 8x and slot 3 bus speed is 1x)?
Question # 3: Can I then install a different NVIDIA GPU than those two I have, like a GTS 450 or another slower card then my N460GTX, and totally dedicate that GPU to PhysX computing? Or must I have the same card as I use as SLI?
Question # 4: Would this configuration give me more graphic power in total even that the bus speed will slow down to half the speed?
Thank you all! Its super to have someone to ask when it comes to things you never thought about before. Yes my GPUs in 16x SLI IS very good, got 6948 points (if I dont remember wrong) in 3DMark 2011 free verision. Have not yet started to OC the system, just came to my mind that PhysX is a important tool in those programs/games that use it.
The problem with physx when there is no dedicated card in a two or three way AFR sli system is unbalanced load and reduced over all fps. Adding a dedicated card will balance the load in sli and enable better performance in physx titles. Second you will be able to run a third cuda client instead of only two.
I have run dedicated physx cards thought out my time and have experimented on several cards. 8400gs before requirements had changed (horribly weak), I have tested a 8600gt in dedicated physx and it wasn't all that great. Then I moved to a 8800gt for dedicated physx.
The physical slot must be able to fit 16x cards however they do not have to run at 16x speed to see worth while gains. 4x in my testing is no bottleneck for a dedicated card however never tested at 1x.
You can run it however 1x might not be enough but who know when pci was good enough for an Ageia PPU (physx card) that is on par with a 8600gt in physx.
I suggest that you look for only a single slot card and that you avoid low end Fermi era cards due to weak overall 32bit single precision floating point performance which is what most applications depend on. A GT240 or a single slot 8800/9800gt if you can find them. If all else look for a GTS450 eco from zotac or the gts 450 from sparkle that does not need a 6pin power connector.
The PhysX GPU only handles the special PhysX features like enhanced water, particles, cloth, smoke, etc. If there are a *** load of PhysX things going on and the PhysX card is maxed out, you can lose some framerate, but otherwise the PhysX card shouldn't impact FPS at all.
Mafia 2 uses really good PhysX destruction and particle effects. There's one part where you're on a big machine gun mounted in a window and have to blast a couple cars (and people) to pieces. So awesome. There's another part where you're in a bar setting and have a huge shoot out, lots of walls get blown apart there. Especially one of those fog-glass window/walls.