The 3770k and multi-gpu usage

l88bastard

l88bastard

2[H]4U
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Oct 25, 2009
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I am running:

-3770k ocd to 4.5ghz
-sniper 3 z77 mobo
-antec high current pro 1200 psu
-(3) Samsung S27A750D 120hz monitors in eyefinity
-Win7-64
-(3) 7970s; 1 Msi lightning, 1 Asus CU2-T, 1 Msi ref card
-12.7beta drivers + 12.7cap 1s
-ULPS is disabled, Core Parking is disabled, hyperthreading is enabled.

When I play BF3 on smaller maps that don't feature vehicles I average mid 80%-high 90% GPU usage with my three 7970s. My FPS rarely dips below 100fps and averages 130+fps

On large maps such as caspian border, Firestorm, Karg, etc, with 64 people, my GPU usage across all three cards hovers from the mid 60s to low 80s. My FPS dips down to 80 FPS and averages 100-110fps

So my question is, are the larger maps with more people, vehicles & action bottlenecking my CPU? Would I be better off with a 3930k or does the 3930k also suffer the same lower multi-gpu usage on the bigger maps?

EDIT 1
Ah, I have discovered the culprit. It is the MESH setting in BF3. If I turn mesh to low my GPU usage jumps to the mid-high 90s! OOOOH wait even better....on further REVIEW I have discovered that the biggest culprit is AMD Tessellation & performance settings in CCC. After disabling tesselation and turning texture filtering quality to performance, I am now able to run Mesh on medium and have high 90% GPU usage on even the largest BF3 maps! Everything is buttery smooth on my trifire 7970 3770k rig now...eyefinity is spectacular at 120+fps!

EDIT 2:
I just got my fourth 7970 in today and Quadfire really puts a hurtin on the 3770k it would seem. GPU usage across the board rarely passes 70%. I did my mesh lowering trick in BF3 and was able to eek out low 70% usage across the board which resulted in 120fps average and super smooth gameplay on my eyefinity setup....however, I would like more GPU usage lol. I wonder if the processor is the bottleneck or if the 8x PCIE slots are the bottleneck. I wonder if two 7990s would fare better in the 16x pcie slots for GPU usage.
 
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Yes 3930K would be alot better in your situation, your experiencing CPU bottleneck because your running 3x cards, and BF3 is really cpu intensive.
 
psyside said:
Yes 3930K would be alot better in your situation, your experiencing CPU bottleneck because your running 3x cards, and BF3 is really cpu intensive.
Click to expand...

This is my guess too. I am hoping somebody with a 3930 or 3960 with 3-4 GPUs can shed some light on their GPU usage in BF3 on the larger maps....before I spend the money to switch out mobos & processors :(
 
What's your CPU usage? I'd be a little surprised if a 3770K at 4.5 is bottlenecking anything. And even if it was, is BF3 well threaded enough to benefit from the extra cores? A lower clocked 3930 might just make it worse.
 
Forceman said:
What's your CPU usage? I'd be a little surprised if a 3770K at 4.5 is bottlenecking anything. And even if it was, is BF3 well threaded enough to benefit from the extra cores? A lower clocked 3930 might just make it worse.
Click to expand...

Lower? he can oc the 3930K to 4.6 with no problems at all.

And yes it is threaded enough.
 
During those dips in FPS, what is your CPU doing? It does sound like you should be on the enthusiast platform.
 
How are the PCI-E lanes divided up in this scenario. The list I read says that z77 comes with 8 PCI-E lanes and that the IB chip adds 16 more. Are you limited to just 8x per card then in a 3x XFIRE config?
 
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You can see exactly where BF3 is spending its render time the performance overlay, useful to see what's struggling more, CPU or GPU.

There's probably a good chunk of driver overhead for 3 cards as well. Even though the game might spawn more than 4 threads, the heavyweight stuff is probably out of the way at that point, but maybe the driver can leverage some free time.
 
Yeah I'd sell the old 4 core and mobo and move up to 6 core with a board that has alot of PCIE lanes for those 3 gpus. If BF3 is your thing and you have tha loot, which it sounds like it. Also sounds like you might pull 120 fps average across the board 2 me with that setup.
 
Use HW Info with Afterburner, and you can chek CPU usage ingame. But it does look like CPU bottleneck...mostly because its multy gpu config.
 
Agree, CPU bottleneck. Just because on has an overclocked or expensive CPU doesn't mean there will not be bottlenecks occasionally.
 
Ah, I have discovered the culprit. It is the MESH setting in BF3. If I turn mesh to low my GPU usage jumps to the mid-high 90s!
 
Glad you found the fix and it made such a huge difference!
 
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