Question 2X4 gB DDR3 1333 Mhz CORSAIR VALUESELECT RAM not detected

[Alin Eduard]

Goodday,

I've upgraded from DDR2 to DDR3 and already have a serious issue. The PC won't boot.

My motherboard is an Asus P5G41C M LX, my processor is an Intel Quad 2 Core Q9650. The motherboards supports 1333 FSB, that's why I've upgraded the processor first - the old one being an Intel E5700 Dual Core. I assume my ddr3 dimm slots work fine, since I've never hit or whatever else the motherboard. I wipe the dust from it regularly and carefully. Each dimm supports 4 gb of ram, either ddr2 or ddr3.
My ram is, as said in the title, 2x4 Gb Corsair 1333 Mhz value select.

BIOS is updated.
CMOS has been reset. As I don't want to mess with overclocking, what else would one suggest ?

Thanks in advance.

Have a nice day.

 

[Alin Eduard]

Also: Speccy shows only two of the the DIMM slots, but I know I have 4, 2x ddr3 and 2x ddr2 - combo mobo. And btw now both the processor and the mobo supports ram's frequency.
Could those ddr3 slots be fried or somehow "deactivated" ? Everything looks fine in BIOS.

Any help would be appreciated. Thx.