Hi everybody,  I've just joined because I wanted to pass on some info relating a problem I've been having with my PC with an ASUS P5K-E motherboard fitted.  I'm sorry if this repeats other threads but I clicked on all the related threads I could find and the system says they don't exist.
Anyway, I have found a solution to the problem of the motherboard failing to POST, on another forum, which works and hope this might be useful to all the P5K-E owners that have been having this problem.  There appears to be loads of you.
The problem is failing to POST with no activity apart from the green LED on the motherboard and the chassis and CPU fans running.  The fault is with the BIOS setting a DRAM voltage of 1.8/1.9v in auto mode when most modern, high performance DRAM need 2.2v.  The motherboard senses that the memory is fitted but the voltage is too low for it to work.
The solution is to by some cheap DDR2 memory, such as Corsair Value Select 512Mb 667MHz, which will run fine on the lower voltage.  Once the PC boots on this cheap memory the BIOS can be accessed and the DRAM voltage set to 2.2v in the Advanced configuration.  Save the config, shutdown, replace the memory with your good stuff and reboot.
I did this and my PC booted perfectly without a problem.
Hope this is useful
Cheers
Peter