14 month old homebuilt desktop won't post (beep), load bios, etc.

Hey guys. I have a problem with my computer that I built last July. Last night, I was playing Crysis 2 and the screen began flickering a bit and then went black. I couldn't tab out or ctrl-alt-del, so I just manually powered down and left it for the night since it was late anyway. Today, I power it on and I have a blank screen. There are no beeps or posts and the screen acts as if it isn't getting a signal (stays in standby mode). Also, the fans and lights all seem to be working but there are no indications of hard drive activity (no clicking of the hard drive and no flickering of the HDD light). One other thing that I noticed is that the cpu fan is running at full rpm's. Usually, it will rev up to full rpm's and then back down to normal rpm's when the computer is turned on. I've looked up what this problem may be and it seems it could be anything from a bad power supply to bad memory to a bad motherboard.

Now, I have noticed the flickering of the screen before when I was playing games but it only seems to happen every once in a while (a few times a month or less and sometimes not even for a month). I plan on swapping the ram with other ddr3 ram to see if that could be the problem. The computer had been a powerhouse and has had little to no problems except for the occassional flickering when playing some games (WoW/Crysis 2). I'm not sure what could be causing this and I really am limited on resources for swapping to figure this out. My parts are all still under warranty so if I can figure out what could be causing this (if anything), I can get a replacement part possibly...

I have tried the following so far:
-Swapped the HDD with another that is in working order with a os installed on it.
-Tried powering on with separate RAM cards installed in different slots.

Think I will try to take the whole system apart and analyze this. It may be my video card but I would hope not (I paid almost $300 for it last July...). I don't think it is my power supply because it is powering the system up and I'm not sure if it's my motherboard because there are system lights and buttons on the board that are working (ie., power and reset buttons).

Any advice is appreciated... :P

Here are the specs of the build:

CPU: Core i7 930
Motherboard: Asus P6X58D Premium
Graphics: XFX Radeon HD-585X-ZAFC (5850)
Memory: G.Skill Ripjaws Series 6GB (3 x 2GB) DDR3 1600
PSU: Corsair HX750
HDD: WD Caviar Black 750GB 7200 RPM 32 MB Cache
Monitor: HP 2159M 21.5" HD Monitor
Case: Antec Twelve Hundred

I'd start with the video card first, then the power supply.

If possible, swap the video card into another computer and see if it works there. If that checks out, try putting a different, lower-power card in your computer, or put the original back and disconnect everything else except the motherboard (no hdds, no cds, etc).

Just because your computer powers on doesn't mean it isn't a power supply problem. The power supply could be going bad and have reduced capacity so it will power the computer on, but not have enough juice to run the extra components properly such as the video card or hard drives.

I just installed the HDD into another computer and it checks out. So, it isn't anything to do with the HDD. I can't install the video card in another computer due to my other older computer having a lower wattage psu. It only has 1 6 pin connector and not the required 2. I could possibly try and hook it up with 1 and see if it brings up the desktop with that but I could risk burning out the video card possibly.

I tried putting a xfx 9800 gt into the computer and I didnt get anything to show up. The screen remained blank and there was no post beeps or anything even with all ram slots empty as well as no HDD or DVD Drive installed (no power or data cables). I heard that it could have something to do with the pins that hold the motherboard up in the case (shorting the motherboard). Not sure if that is it but it's worth a try.

Okay, I just found out something interesting... It seems that I actually did have 2 6 pin connectors with the psu in my older pc. I hooked up the video card to them and powered on. It seems to be doing the same thing as in the 14 month old pc. The thing that is confusing me is that I installed a 9800 gt in my newer computer and it wouldn't load anything either even though I KNOW that the 9800 gt works because I have used it in the older computer to play games and such.

I'm not sure what to think here... Maybe it's the video card AND the pci slot? Maybe I should try a different pci slot with the 9800 gt... :P

Edit: I just installed the 9800 gt in a different pci slot and lo and behold the system boots and runs its posts and tests. Now I need to try my 5850 in the same slot to see if I can boot. If not...then it probably IS the video card. :-/

Edit 2: Ok, I've basically concluded that it is my 5850. I installed it in the same exact slot and got nothing. Not even a signal for the monitor. I reinstalled the 9800 gt in the same slot again with the HDD and everything else installed and it loads to the desktop. I'm pretty sure that means that it's my video card. Anyone else agree? At least the video card has a lifetime warranty. I wonder if they will fix it or give me a newer model since they have deactivated my video card on Newegg....