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I left my early '09 Mac Pro on while traveling so it could handle some security cameras and do some cron jobs. That worked fine. I got home last night, checked some things on it, and still all well. This AM, I started to fire up some programs on it and it first was unresponsive (spinning beachball) and then froze. When I tried rebooting, I now face the "White Screen of Death" after the startup sound.

All startup key combos fail to boot: I can't start Safe, Hardware Test, OS X Recovery, boot from CD, etc. I can reset PRAM in the sense that it reboots the computer, but it doesn't change behavior. The one behavior I see is that if I hold Option to try to get to Startup Manager, I get a responsive mouse cursor (but no further menu / icons, etc.)

I've tried resetting the SMC by plugging/unplugging. I've tried re-seating my RAM banks and booting with only one RAM bank from either slot.

This has been an extremely reliable computer but it seems like in the past few months I've experienced more kernel panics.

First: Is there any obvious thing that I can do to try to further isolate / debug my boot problem?

Second: Is this consistent with a bad power supply? (I'm just thinking that running along at some near-idle mode for 2 weeks and then get sudden power demands might trigger a failure on a marginal power supply.) Is there any way to diagnose that on my own? (I live on an island with limited retail tech support.)

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Don't sound like a power issue. Could you check your HDD? – Nov 4 '12 at 0:52
How can I do that without booting? I can check cables, but that's about all. – Larry O'Brien Nov 4 '12 at 2:24
Most likely not a PSU, generally when those fail the symptom is the computer will fault randomly. So during times where the draw is low (possible rebooting cycle), it would be relatively okay then on a high draw - it would reboot. (generally). No system beeps or anything? – nerdwaller Nov 4 '12 at 4:02
@LarryO'Brien You'll have to take the drive out and hook it up to another computer (may void your warranty). Alternatively, if you have an OS X DVD or USB stick, you can follow this guide to load the diagnostic program. – Nov 4 '12 at 15:25

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