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SLI Disable or Not?

A

ATITek

Limp Gawd
Joined
Aug 6, 2004
Messages
138
I am playing Batman: AA and was wondering if I am better playing with SLI w/ PhysX on or SLI Disabled w/ PhysX on.

Here are my system specs:

Asus P5ND nForce 750i SLI, Socket 775, PCIE,DDR2
Intel Core 2 Quad processor Q9450, quad 2.66GHz cores, 12MB L2 Cache
DDR2 Memory 4096MB Corsair XMS2 DDR2800
2 x 512MB EVGA GeForce 8800GT DDR3 in SLI, PCIE,Dual DVI/HDCP
Integrated High Definition 7.1 Channel Sound
750GB Hitachi 7200rpm 16MB Cache SATA 300 w/NCQ
Windows Vista Ulimate 64-bit


Also, I assume I only need to Disable SLI from control panel to dedicate one card to PhysX processing correct?



I ran a bench in the game and this is what I found:

PhysX w/ SLI
Min: 32 fps
Max: 60 fps
Avg: 54 fps

PhysX w/ SLI Disabled
Min: 33
Max: 60
Avg: 54



Why are they so close based on my specs?
 
The game does seem smoother with SLI disabled yet the bench says otherwise....

Any idea why?
 
I would still that I would benefit from dedicated card vs. SLI. The 8800GT should not be at its limit based on my game settings...
 
Can I dedicate a card to PhysX with two of the same cards in SLI? Nobody has really answered my question.
 
Atech said:
Are you kidding us?
Click to expand...

Read the thing again... and figure out what tone it was sent in... and notice the overuse of the ":rolleyes:" emoticon... there is a reason behind it...

Read, think, post.

Don't just post... and never think!
 
jeremyshaw said:
Nope. You cannot use a card in Physx, while it's also in SLI.
Sorry.
Click to expand...

If I disable SLI in nVidia Control Panel then the second 8800GT will automatically become dedicated to PhysX correct?

That is what I meant to ask.
 
no, when you turn off SLI in nvidia control panel, there is another option within the same window that allows you to turn on physx to the secondary card in your system. this may have something to do with your results - you may not have had the right options checked in nvidia control panel.

also, double check which driver set you are using, I think in the last revision of the nvidia drivers there was an increase in fps in batman. good luck!
 
JacobC1983 said:
no, when you turn off SLI in nvidia control panel, there is another option within the same window that allows you to turn on physx to the secondary card in your system. this may have something to do with your results - you may not have had the right options checked in nvidia control panel.

also, double check which driver set you are using, I think in the last revision of the nvidia drivers there was an increase in fps in batman. good luck!
Click to expand...

I just read the descriptions in nVidia Control Panel it says something like:

"Disable SLI to run in multi card mode. If you have two identical cards then the GPU not focused on your primary monitor will be dedicated to PhysX processing...."

I have two identical cards and hence that is why I do not have an option to select what card I want PhysX to run on. I can only enable or disable PhysX. I am using the newest nVidia drivers, 191.05.

The reason I am confused is all the screenshots on the forums show a drop down to select what card you want to do PhysX processing. However, I have two of the same cards.
 
Thats what I mean, you can enable or disable physics, its not an automatic thing that turns on by itself like you were asking.
 
JacobC1983 said:
Thats what I mean, you can enable or disable physics, its not an automatic thing that turns on by itself like you were asking.
Click to expand...

My concern is that it never showed me the drop-down menu to select one of my 8800Gt's to do PhysX processing. It does not matter I guess.
 
nope. just set it to on, the drivers know which DVI output you are using for the monitors you are running, and uses the other card that doesn't have any monitors running from it.
 
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JacobC1983 said:
physx is running on the CPU, not the GPU
Click to expand...

That's not right at all, it 's wrong in fact. PhysX runs on the GPU, and doesn't take nearly enough use of the cpu in fact, especially in Batman.

If you want run PhysX you should disable SLI, you should get better performance that way, I've seen at least one article about it and that was definitely the way to go. It's also the way that I played through the game, with the exact same cards.
 
Physx can run in software which is handled by the CPU if there are not cards in the system for dedicated physx processing. It doesn't work nearly as well and sometimes causes performance hits as seen in Batman in this link, but can be utilized by a single CPU thread in core i7 and works in several other games as well.

Have a read and educate yourself about software run Physx by CPU - it is an alternate option if there is no dedicated PPU as the OP would have if his system was enabled for both SLI and PhysX
http://www.nvnews.net/vbulletin/showthread.php?t=141180
 
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