Computer freeze with two memory sticks

[Techmates]

Hi, I'll be very grateful if someone helps me out of this problem and apologize if I have posted in the wrong way. My problem is when I put two RAM in two memory slots in my PC it becomes unstable and not boot the operating system or freezes after minutes, hours or sometimes. Both memory cards work independently but as soon as I put in both, the system will become unstable and freeze.

[Terrextre]

Please check motherboard for its standard memory support it may be DDR3 2200/1333/1066/800. There may be problems with RAM 16ooMHz?
Is this a new version or build? Did different RAM worked before?
Make and model of the 620W power supply? Do you have XP installed, more than one hard drive? Try booting with only the hard disk with an operating system and disconnect all other. This may help you.

[Balamohan]

Hi guys, Thank you for having responded to my question and apologize for the slow response. Please let me know if you want more information. The PC is a new version and has given me problems since it was assembled. I considered the ram compatibility issue, but I figured it would not be a problem if it runs slower than its recommended value. Maybe this is the problem? XP is not installed on any other hard drive and not on the same drive as Vista. The problem arises when you have only one hard drive is connected. Thanks for your guys suggestions. I look forward to hearing from you

[Alexisus]

I never build a system without the ram match to the motherboard one of the things that can go wrong.RAM upgrade: Dell, Apple Mac, HP, Compaq. USB drives,flash memory cards, go to site and match the motherboard to a specific model number of memory You do not have to buy any of them, without any match otherwise it will not let your system. this is becoming a much more important issue than ever in the past.

[Apple.Mac.Rocker]

Thanks for the help, guys. I ended up getting some RAM - 2x2GB of transcend however, the PC is still susceptible to lock. It has not failed yet in XP, but Vista always crashes after I load boots and one or two programs (eg Firefox, VLC).Appears to be stable in XP with the new 4GB of RAM, although not clocked so many hours with the PC yet.
Suspected software problem? Thanks for giving reply.