I have a ASUS EN8400GS.In every new game requirement it says that minimum of nvidia 7800gt excluding nvidia gforce 8400gs.why is that only this graphics card excluded.when i run the test in system requirments lab with the game X-Men Origins: Wolverine it says so.will any body say why
I'm guessing your assumptions of video card performance is rather simplistic; meaning you are assuming the higher the "number", the better it is. For example, you rather have $120 than $100, right?
Video cards are a little more complex than that. First number denotes the generation or card series. Therefore, nvidia 8xxx cards are newer than 7xxx cards. The next series of numbers more or less defines the performance level of that series.
The 7800GT is rather high end for that series while the 8400GS is on the low end for that series. Since those cards are only one generation apart from each other, expecting a low end card of a newer generation to outperform a high end card from the previous generation is a bit unrealistic. The specs that isamuelson proves that point.
You'll need to wait a few generations for even a mid level card to be on par with an older high end card in terms of overall performance. For example, the ATI HD 4670 mid level performance card is a little faster than the high end X1900XT from 3 generations ago.
Unfortunately, if the 8400GS is not capable of playing any of the games you want to play then you only have two choices:
1. Don't play games.
2. Upgrade your card.
Before spending anymore money on a video card, you should look at benchmarks to determine if the video card you wanna buy has good enough performance. I like xbitlabs' reviews: