[Cube] Need some troubleshooting help

[Fred Terry]

Howdy,

I have a problem with my upgraded Cube that I haven't been able to figure
out, so I'm looking for suggestions.

The Cube was originally a 450MHz model that I've upgraded with a GigaDesigns
1.2GHz processor. I installed a fan when I did the processor upgrade. I have
installed a Radeon 7500 video card with a heat sink and fan. The hard drive
is a Western Digital 320G that I've partitioned with the HiCap driver. I'm
currently running Leopard, but the problem was happening on Tiger before the
upgrade.

The problem is that the Cube will freeze unexpectedly while I am copying
large files across a network connection or between the internal and the
external drive. It will also freeze when I am playing a song in iTunes. This
is repeatable and happens every time I try to use iTunes. The Cube has an
iSub attached along with the standard speakers.

I have replaced the motherboard, the video card, and the PMU. I have also
tested the RAM and it consistently passes. I have not replaced the
GigaDesigns CPU with the original processor, but I'm planning to do that
over the weekend. 

I appreciate any suggestions for what to test/replace next.

Thanks,
Fred