You've added a lot of stuff, I was thinking the PS is overheating or being taxed. I have an old MDD that has add on USB and firewire cards and 4 HDs. If I use a beefed up video card I need to unplug a HD or two to keep it from randomly shutting down.
Are all the fans working? If you leave the case open, possibly with a small fan on it does it shut down? Maybe you need a PCI exhaust fan or two to pull the heat out of the case.
Xplain's use of MacNews, AppleCentral and AppleExpo are not affiliated with Apple, Inc. MacTech is a registered trademark of Xplain Corporation. AppleCentral, MacNews, Xplain, "The journal of Apple technology", Apple Expo, Explain It, MacDev, MacDev-1, THINK Reference, NetProfessional, MacTech Central, MacTech Domains, MacForge, and the MacTutorMan are trademarks or service marks of Xplain Corp. Sprocket is a registered trademark of eSprocket Corp. Other trademarks and copyrights appearing in this printing or software remain the property of their respective holders.
All contents are Copyright 1984-2010 by Xplain Corporation. All rights reserved. Theme designed by Icreon.