No big CPU to run it with, but a trusty Intel Core 2 Duo E4300
overclocked at 2.4GHz:

6 Point Of View Geforce 8400GS Overclocking

As it is a low-budget Video Card, throwing the heavy 3D Mark 06 on it will
hammer it for sure. Thus, I ran 3D Mark 05 to evaluate where it stands.

13 Point Of View Geforce 8400GS Overclocking

Almost 3,000 points in this benchmark. Not too impressive, but can’t ask for
too much at that price. Notice that the GPU Core clock is 460MHz, Shader
Clock is 918MHz and DDR2 Memory clockspeed is 300MHz.
You also see it runs
at 47C in idle state.

16 Point Of View Geforce 8400GS Overclocking

Loading the GPU doesn’t push out too much heat either, just
51C loaded.

So I pushed the graphics card by simple overclocking means.

14 Point Of View Geforce 8400GS Overclocking

Core goes to 580MHz, Memory to 500MHz out of the box. That’s a 26% overclock
on the core and a 67% overclock on the Memory, pretty impressive headroom! Just
doing that brings performance up by over 50%! That’s almost similar to as
when one run Dual SLI Video cards of these.