I have a Shuttle AK31 v3.1 that I built a good 6 or 7 years ago and has kicked butt since Day 1, but is now giving me a prob.
I lost video, so in trouble-shooting everything, when I boot I get a 3 second beep with nothing on the board.
No RAM, no drives, no keyboard/mouse, nic, video nothing. Just the power supply and the CPU (XP1700) and I still get the 3 second beep, repeating itself every 5 seconds or so. When the keyborad was plugged in it would flash and that's about the only response I got.

Should I look at the CPU first? If so how can I tell if that is toast?
Or should I look at the mobo and again how can I tell?

If I had to pick one to replace which should I go for, the least expensive or ...?

Thanks all!

If it's 7 years old, might as well get a new PC. It's not not worth troubleshooting a machine that old for an intractable problem. Even if you find the problem, how do you replace the failed component? Ancient parts are hard to find and tend to be expensive.