My pc isnt DETECTING my hdd in Bios

im running an ASUS psn -d mb, with 4 g ram, an intel dual core processor and a pci ati sapphire card, running win 7,untill yesteday i had two internal hdd one western digtal 250G and one seagate 1tb both sata drives,my computer froze up and i restarted, and this is where the issues started, got a bsod saying unmountable boot volume, so opened up the case to see if there was any loose connections etc, not that i could see.

so turned everything back on and then only one sata drive was showing my dvd drive wasnt showing up either, so swapped the cables about too see if that was the problem, nope still no joy

now no drives are showing have swapped out my sata dvd drive for an ide one and that is showing up in bios,

have try to put in a ide hdd but that isn't showing up either

i have TRIED to see if the drives are getting power but dont think they are( can't hear them spinning up or anything)

so im at a complete loss where to turn next, im thinking it may be a faulty power lead that isnt getting jucie to the drives, everything else is powered up, systems fans x 2 ,cpu fan, card fan, and ide dvd drive are all getting power.have MANAGED to boot using a external hdd with linux on it, so it shouldnt be a mb issue as then it wouldnt boot at all.

Any help or pointers would be great I had a similar issue a few months back. My PSU unit weakened and couldnt handle my 2 HD's + everything else. I replaced PSU and all was well except for that I had to reformat my one hard drive that must have been written too on insuficient power.

Prior to swapping PSU my system would freeze up, bsod, etc until I removed 1 of 2 HDD's. I then added a different SATA HDD and symptoms came back. Swapped a cheapie no name PSU for a 460watt thermaltake power supply and then all was well.Thanks for quick reply will have to buy a new psu at the end of the month when I get paid and see if that makes a different.