Though SLI is real fun and a very fast way to quickly get more performance, it also effectively ads more 'load' on your power bill. Each GeForce 9800 GTX+ can consume up-to ~150 Watts per card when 100% stressed.

Typically this number is lower as your GPU in a lot of situation will not reach that TPD (wattage peak). On average we expect a 150-200 Watt power draw during gaming, per card.

We'll now show you a tests we have done on overall power consumption of the PC. Looking at it from a performance versus wattage point of view.

The methodology is simple: We have a device constantly monitoring the power draw from the PC. After we have run all our tests and benchmarks we look at the recorded maximum peak; and that's the bulls-eye you need to observe as the power peak is extremely important. Bare in mind that you are not looking at the power consumption of the graphics card, but the consumption of the entire PC.

Our test system contains a Core 2 Duo X6800 Extreme Processor, the nForce 680i mainboard, a passive water-cooling solution on the CPU, DVD-rom and a WD Raptor drive. The results:

• PC 100% usage (wattage gaming Peak) = 413 Watt (SLI)

The monitoring device is reporting a maximum system wattage peak at 413 Watts with SLI. With that in mind .. let's start some games and see how well they perform.

Software Used

Now we begin the benchmark portion of this article, but first let me show you our test system plus the software we used.

Mainboard

nVIDIA nForce 680i SLI (eVGA)

Processor

Core 2 Duo E8400 3 GHz / 1333

Graphics Cards

Various

Memory

2048 MB (2x1024MB) DDR2 CAS4 @ 1142 MHz Dominator Corsair

Power Supply Unit

BFG ES series 800 Watt  PSU

Monitor

Dell 3007WFP - up-to 2560x1600

OS related Software

Windows Vista 32-bit
DirectX 9/10 End User Runtime
NVIDIA ForceWare 177.39
NVIDIA PhysX driver 8.06.12 (CPU acceleration).
NVIDIA nForce 590/680i platform driver (latest)

Software benchmark suite

Mass Effect
Race driver: GRID
3DMark Vantage
Call of Duty 4
Crysis
Ghost Recon: Advanced Warrior 2
S.T.A.L.K.E.R.
F.E.A.R.

A word about "FPS"

What are we looking for in gaming performance wise? First off, obviously Guru3D tends to think that all games should be played at the best image quality (IQ) possible. There's a dilemma though, IQ often interferes with the performance of a graphics card. We measure this in FPS, the number of frames a graphics card can render per second, the higher it is the more fluently your game will display itself.

A game's frames per second (FPS) is a measured average of a series of tests. That test often is a time demo, a recorded part of the game which is a 1:1 representation of the actual game and its gameplay experience. After forcing the same image quality settings; this time-demo is then used for all graphics cards so that the actual measuring is as objective as can be.

• So if a graphics card barely manages less than 30 FPS, then the game is not very playable, we want to avoid that at all cost.
• With 30 FPS up-to roughly 40 FPS you'll be very able to play the game with perhaps a tiny stutter at certain graphically intensive parts. Overall a very enjoyable experience. Match the best possible resolution to this result and you'll have the best possible rendering quality versus resolution, hey you want both of them to be as high as possible.
• When a graphics card is doing 60 FPS on average or higher then you can rest assured that the game will likely play extremely smoothly at every point in the game, turn on every possible in-game IQ setting.
• Over 100 FPS? You have either a MONSTER of graphics card or a very old game.