This is my first time writing on this forum, but I've been reading it for a long time. I'm not an expert on computer, but I do know a lot. Anyways, to the problem at hand. This is my system:
Asus P5n-e-sli (650i)
Consair 667mhz ram
I have gotten it to work, and everything was fine and dandy until I turned it off for the night. The next morning, it would not post. No beep or anything. So, I spent that whole day trying to figure out what's wrong. I could get it to occasionally post, and boot by removing ram or turning off the power supply for a while and then back on, or by randomly unplugging DVD drives and HDD and the such. Once I got it posting, it would work just fine until I turn it off for a long time again.
So, this is a very frustrating problem. Please help!!!
you might be at the limit of your power supply..generic supplys are usually ok for basic needs..but gaming rigs going by your list need good clean power...enermax,ocz,pcp&c,etc.
I know it doesn't sound like it's important but beleive me it is!
Thanks for the help. Okay, I've gotten a hold of my friend's 500Watt OCZ PS and tried it out. At first, with just the MB and graphic card hooked up it posted just find. After I added the HDD and DVD drives, and restarted, it wouldn't post again. When i unplugged the other HDD and DVD drives, it still wouldn't post. (also, i tried starting it with the graphic card unplugged and a weird long beep sounded, is this bad for my graphic card?)
I don't think so. 500watt is 100watt over the recommended power requirement. Also, i truely believe this is a motherboard problem because i've already tried it with another PS. Plus, once I do get it to post and boot, it works perfectly without a hickup! I know because I've spent 3 hr playing Bioshock on it.
Im starting to think that my mb is bad. LoL, this is going to be the first asus product that failed on me... Anyways, I'll try to reground my mb.
 I don't think it's a grounding problem either, because the light on the mb is always green when the ps is connected. I'm really leaning toward the MB being bad, in which case I would be out a $100 for a new one.
Your power supply is still likely a culprit here, according to various sources the 8800GTS wants a PS with 26A on the 12V rail, considering that yours theorectically was capable of only 28A when new, it is quite possible that it can't deliver the required juice now. Not that I would discourage anyone from replacing a 650i board with something better, but then again I haven't been impressed with the nVidia chipsets for the last few iterations.
Note: You didn't say what brand etc your video card was, however note that a card such as the BFG 8800GTS 640MB OC version wants to see a min 28A avail on the 12V rails.
LoL, I do have a BFG 8800gts oc. Got it through a rma because my 7900gt oc went bad. But yeah, I did not know that the OC version required 28A... Still, would this cause the MB not to post at all? I should be able to get to the bios at least.