Crash games on Vista

Often when I play a game (such as Left 4 Dead in particular but not pub) game crash:
- However I reboot my PC with a blue screen (just type bios) with a counter that increases from 0 to 100 and as soon as it is a 100 reboot it (it's pretty fast)
- It is the games and cutting back on the desktop
- It is cutting the game, back on the desktop and launched me an error message saying the game does not respond.

I learned that this could very likely be due to the ram.

I have a motherboard P5W DH Deluxe and my memory slot are available as follows:
(1A) (1B) (2A) (2B)

The manual is to advise the pair of ram slot on the same number but some people told me to put slots on the same letter.

I have 2 strip ram 1GB Corsair PC6400 CL5 and 2 Corsair 1GB PC6400 CL4.

How will I have to solve this problem.

Thank you in advance.

Can you give us more details about your configuration ?

You have different timings of barrettes which can actually cause problems in case of bad positioning: I groups on the same figures as specified in the manual ... but after all I really do not know this card so good ...

In bulk:
- Make a memtest
- Check the configuration of memory timings in the BIOS. To increase the need for a test.

Overclocke graphics card?
error messages in the event handlers?

I have the latest graphics drivers but I had already heard that the series of 9800 could crash.

I will try to save only CL5. I believe that the adjustment is automatic.