Hi guys....
 
just got a pair of Corsair 2GB DDR2 XMS2 Dominator PC2-8500C5 TwinX for my PC. Am using an ASUS P5KC mobo with Q6600 processor. When i installed the RAM the PC did not post.  
 
Removed one stick and everything was fine except the RAM was running at 800mhz... which is fine coz i can manually set it to the right speed.
 
Tried the other stick by itself and the pc did not post.  
 
I have tried two sticks of Corsair 800mhz RAM and everything is fine.  
 
Tried setting speed, timings and voltage manually in the bios and then putting the new ram in but the problem persists.  
 
My question is simply... is the RAM faulty? or am i missing something?

Based on my experience, I would say it sounds like a bad stick.
 
However, I would suggest tuning your bios to stock settings if you have any overclocking going on.
 
The ram will downclock to whatever the bios tells it to. If that second stick still doesn't work with stock bios settings. I doubt it ever will.  
 
If you do get your bios to post with the troublesome stick, I suggest booting up off a disc with memtest86. That will tell you if the module is bad.
 
If that fails call up the company or RMA to the store.

just as i thought... thanx.