I recently decided to try the cheapest possible Athlon 64 build I could. I went with a $30 Cooler Master PSU, old case laying in closet, 2800+ retail, 1 stick of 512 3200 Wintec RAM, Aopen mobo, refurb. All parts from newegg. Used a 30gig HDD I had sitting here as well.
I have had nothing but problems with this setup. First it was power, so i bought the coolermaster. Second, it was either the board or the RAM. I originally had a Biostar board, never had problems with them in the past. I switched to the Aopen board which worked much better, but I still get random crashes, usually during Source. FAH crashes once in a while, but that seems to have fixed itself once i took the -forceasm off. I also clocked the proc back down to 1.8, I had it at 2.0
For the extra $50 it would have cost to get retail good parts, id say go for it. Definitely not worth the hassles of returns and troubleshooting. I love buying good namebrand parts that work everytime. I did narrow my problem down to the RAM though, either its a bad stick or the RAM just sucks. While posting in a different forum on this, someone had mentioned timings. I checked and sure enough the RAM timings were diff for the 2 sticks i had in there, so i backed off to 1 stick and that fixed most of my problems. The setup runs great for normal daily use, but will crash out if you try to work it, lol. Perfect setup for mom, hehe.