ARMAIIMark - slower with SLI

[GunSlingerAUS 10]

Hey folks,

Just noticed something real weird - my system benchmarks slower with SLI enabled.

Specs:

Core 2 Duo overclocked to 3.8GHz (100% stable with Intel burn test)

4GB DDR2-800

eVGA 780i SLI FTW mobo

2 x 8800GTX

2 x WD 500GB in RAID 0 mode

Vista Ultimate x64 (fairly new install - around a month old)

NVIDIA 186.xx drivers

eVGA SLI enhancement

vysnch forced off

Game settings:

Default high setting

1920 x 1080 for both resolution settings

-winxp switch enabled (note, I'm using the Steam version of the game)

Benchmark results:

NVIDIA SLI recommended: 2314

AFR2 SLI: 2102 (this is the only mode where the SLI indicators work - NVIDIA recommended does not work)

SLI set to Single GPU: 2527

Absolutely bizarre behavior, indicating that this game and SLI has serious issues... among many others. Sigh.

Anybody else got different results in ARMAIIMark with a similar setup and graphics settings?

[Horus 83]

error

Edited July 5, 2009 by Horus

[beugnen 10]

that's only a 9% improvement, hardly significant; in addition subject to +/- test error

[GunSlingerAUS 10]

that's only a 9% improvement, hardly significant; in addition subject to +/- test error

A +/- 5% or less margin for error is usually acceptable when testing hardware. And regardless of that, wouldn't you expect an improvement with SLI enabled, rather than a decrease, even if it is only 9%?

Having said that, it appears that on my system the ARMAIImark benchmark is CPU limited, as performance online feels better while playing with SLI enabled.

[Yapab 10]

The game is very CPU limited.... even at 3.8ghz on a dual core (i presume E8400 or above).

SLI when enabled makes the CPU work harder as the CPU has to do some of the SLI communication work... therefore there are less CPU cycles for the game.

This maybe why you get higher marks with SLI disabled... however in the game you will notice better smoother fps with SLI as the game is not CPU limited in non town areas.

I think the game needs some serious optimisation as there is not that much happening for such fast mhz CPU's to be bottoming out.

Yapa

[beugnen 10]

A +/- 5% or less margin for error is usually acceptable when testing hardware. And regardless of that, wouldn't you expect an improvement with SLI enabled, rather than a decrease, even if it is only 9%?

Having said that, it appears that on my system the ARMAIImark benchmark is CPU limited, as performance online feels better while playing with SLI enabled.

agreed, normally SLI should offer improvement.[1]

how many test runs did you run though when you got the 9% improvement? is it reproducible? do you still get the same result after quitting and re-running the game? finally, try the test again after rebooting. this will reduce the error margins i suppose but more importantly whether the improvement was a curious one-off.

let us know how you go

-------------------------

[1] there is a disturbing trend of games that are immune to SLI/crossfire. initially i was reasonably sure that we were told such things was in the driver level and that games did not have to be programed against it. there are conflicting reports about this today.

---------- Post added at 08:22 AM ---------- Previous post was at 08:11 AM ----------

The game is very CPU limited.... even at 3.8ghz on a dual core (i presume E8400 or above).

SLI when enabled makes the CPU work harder as the CPU has to do some of the SLI communication work... therefore there are less CPU cycles for the game.

This maybe why you get higher marks with SLI disabled... however in the game you will notice better smoother fps with SLI as the game is not CPU limited in non town areas.

I think the game needs some serious optimisation as there is not that much happening for such fast mhz CPU's to be bottoming out.

Yapa

interesting, but im not sure that is entirely true. in SLI cards are configured as master and slave. data is sent to the master and relayed to the slave via the sli bridge thus excluding the need for cpu or motherboard intervention. even in systems without the bridge, the motherboard is able to send data between cards in pcie.

i couldnt quite understand what you meant by cpu, so ill just recap. it is widely known and proven that the game is cpu-bound. gpu is making insignificant impact to game performance.