It sounds like you have quite a few drives packed into your system.
You say that the problems go away when you disconnect some of them.
This leads me to suspect that the power supply is failing, or just
not adequate.

Assuming that you have access to an oscilloscope, you could plug
everything in, and check that the voltages, especially +5 V,
never fall below 95 % specified value by using the single sweep
trigger (you may have to preset it using a voltmeter and a
variable voltage or potentiometer).

It might be simpler just to swap power supplies.

Is the Power Supply still under warranty?

One likely problem could be a failing capacitor in the power supply.
Unless you are experienced with working around lethal voltages, stay
out of the power supply box.

Hope this helps.

Boyd Ramsay

[log in to unmask]

            PCBUILD maintains many useful files for download
              on our web site - visit our download page at:
                     http://nospin.com/pc/files.html