problem with random reboots

[sakoula]

Hi,
I have a Asus P8P67 B3 with an i5 and installed 10.6.7 getting help from this wonderful
forum.
On installation I have connected
8 GB RAM - G.Skill RipJawsX 8GB (2x4GB) DDR3 1600MHz Dual Channel Kit F3-12800CL9D-8GBXL
boot SSD - 120GB OWC Mercury Extreme Pro SSD
and
GPU - XFX Radeon HD 6870 1024MB

Everything went fine and I have used the system for a while (not much time really).

Yesterday I added another 8GB same kit, and a Samsung Spinpoint F3 1TB SATA 32MB (HD103SJ) 7200rpm.
I also added a PS3 camera and used macam to check if it was working.
I started working on the system installing software and rsyncing data from an external dusb 2.0 drive.

After 30minutes on the system (or so) the screen went black while I was working and
the machine rebooted. Once it came up it mentioned on a dialog box that a usb device
was not functioning correctly because it required more power and if that device had a
power input to plug it directly to the power.

I imediately unplugged the webcam and the external usb disk (2.5'' inch 1TB Lacie without external power) and I tried rebooting. The machine came up again and I continue using it and after 5 minutes I saw the same thing (immediately black screen and reboot).

I have the keyboard and mouse and monitor connected through a Belkin KVM (http://www.belkin.com/uk/switch2/)

Any ideas on how to attack the problem?

Thanks!

 

[SJ_UnderWater]

are you sure your power supply can handle this load? you haven't mentioned it so I'm assuming you don't know its rating off-hand

 

[sakoula]

Bequiet DARK POWER PRO(P7) 550W.
It is not that big but should be adequate for this system, shouldn't it?

I just tried running my system through the be-quiet psu calculator
and it gives me 3 possible PSU options for my system:
an 480W, an 550W and a 650W.

 

[SJ_UnderWater]

have you checked the various logs in Console.app (/Applications/Utilities)? Are there any messages around the time of the restart?
OS X, like any other unix system, favors kernel panics to automatic restart (like windows), so it must be some hardware instability. If you have access to a Kill-A-Watt meter, try monitoring the electricity usage. It seems like it may be dying as the system heats up and the fans do (or don't!) kick in. Multibeast includes a program that shows various temperature readings on the motherboard.