Bench test mobo, power-on problems

Hi
I have my motherboard sat on a cardboard box attached to hard drive with OS installed,graphics card,2 sticks of memory,keyboard and mouse and everything seems to be working fine apart from powering/starting up problems.
On pressingthe power button on the case sometimes it starts sometimes it doesn't.
I have also tried another PC case thinking it might be a dodgy power button but the same thing happens with the other case.
Sometimes i have to disconnect the power from the wall socket before it will start up.Once it starts up it is absolutely fine and stays on with no problems.
Do I have to change something in the bios
The mobo isn't a new one it is a MSI 6526 ver 3. and I have a pentium 4 1.8gHz CPU
Any advice would be gratefully appreciated
Thank you

Always disperse the internal voltage (by removing the power cord, then holding in the ON switch for 30 secs)

Make sure to disconnect everything internally (ie all addon PCI devices, and CD/DVD connection and floppy connection (if you have one) from the motherboard

Actually here's a good BenchTesting guide.

One last possibility, I have had faulty case and CPU fans cause boot up issues.
And faulty Power Supplies (doing strange things)

You should also reset CMOS to defaults

Nice post kimsland,

" I have had faulty case and CPU fans cause boot up issues"...

"Faulty cases" are really bad power supplies and power switches. That Bench Testing Guide is great!