Vista 64 bit doesnt read all 4 sticks

I had vista running fine, reading all 4 sticks fine for a good 3 months, installed a new psu, still detected them fine, one day a month later i boot up and it just reads 3 gigs :S.

I tested the sticks, they all work, bios reads all 4 sticks, placing the sticks differently does not rectify the issue, neither does using 3 in random places, still reads just 3.0 gigs, i dont know what the crap the problem is since my windows whatever experience didnt go down anywhere. I have no instability issues what so ever, nothing heats up, havent played supreme commander so icant say if performance decreased by 0.5% or not

New psu is Thermaltake toughpower mod 850w if anyone wants to know, i think it happened when I lost power and got it back, but...bios reads all the sticks, i dont know what gives, but maybe you do

I brought them from the fastest timings to the absolute slowest availible for all timings, no luck. Lowered voltages, hightened them, lowered to 667.
This is weird :S I thought you were absolutely right since I remember recently reseting my bios and only remembering to highten my ram voltage and not the timings, which I had previously left slower when trying to fix ghost restart issues a few months back

ran memtest, no errors :S

Does the BIOS see all 4 GB of memory? Are you using Vista 32 or Vista 64?

Sorry I forgot to mention im running 64 bit, and as previously stated, yes bios reads it all.

How exactly do I enable memory remapping, i havent seen any words resembling those in my entire bios

I don't know what motherboard/bios you have - So all I can say is to read the manual that came with your mobo and find out...