For bad caps see-:
http://home.earthlink.net/~doniteli/index27.htm
More interesting reading-:
http://www.niccomp.com/taiwanlowesr.htm
http://www.pcmag.com/article2/0,4149,939887,00.asp
Power supply could cause the problem and so could overheating.. fans
becoming choked with dust etc.
You will get bios post, Power On self Test (bios boot as many refer
to) with all the drives disconnected inc. the hard drive leaving just
the CPU, RAM and Graphic card you won't get past bios without the
Graphic card.
Davy