HELP! I just entered into the realm of those who build their own machines. Always wanted too, never did, changed that, and here I am. Its been running great since the build date (5/25/06) until yesterday (6/15/06). I turned it on, it powered up, but that is all. H.D. light stayed solid for approx. 20 sec. and went off. No video at all, and would not turn off without holding in the power button. I did notice if I hit reset, the monitor would flash from "no input" to solid BLACKAND back to "no input". I tried resetting a couple times, disconnecting power, and reconnecting with no effect. I then moved the computer to another room to open it up, powered it up one more time to make sure and it booted FINE. Played HL2 for a couple hours, turned off, slept, powered up and same problem was back again, with no change since. I checked all internal connections and found no problems. Would appreciate any helpful advice. Thanks!
:-?
System specs

Windows XP SP2
Panda Platinum AV and IS
ASUS A8N32 DELUXE with Athlon X2 4200+
2GB Corsair XMS 3200
EVGA Nvidia 7900 GT
WD 250 GB SATA II 3GB/s
HP DVD +RW DL
ASUS DVD X16
are u sure u put the power and reset button jacks in the right place?yes... it has been running fine for a couple weeks
What brand power supply and what size? Was it new? Any power surges lately?power supply came with case (xg dragon) and is 500 watt. Already checked power supply ok. I believe it is either the MB or CPU, how do I determine which is bad, without being able to hotswap?
Are the parts new enough to have some sort of warranty? Where did you get the components?
everything but the MB came from Newegg. The MB came from Zipzoomfly. They were purchased on 5/13/06. warranty would be from manufacturer. Should I just send both parts in? I did not use the stock cooler with the cpu, so I'm worried about sending it back. WHATS the best way to get the thermal grease off the cpu?

An alcohol swab or moistened Q Tip will remove the grease. Use SPARINGLY! Newegg should be fine with an RMA. Not sure about Zipzoomfly.

I'm also not sure about the power supply. How did you test that? How did you decide on that? It looks like several reviewers had problems with premature death:

http://www.newegg.com/Product/ProductList.asp?Brand=10456&N=2010320058+50010456&Submit=ENE&Manufactory=10456&SubCategory=58Swapped for a known good power supply and problem remained, and to make sure, checked voltages with a multimeter.Sounds like you have done all the reasonable and PROPER things. Assuming it was a correct build I would next look to the motherboard, and then the CPU as culprits.