Spec:

Brand New:

AMD Phenom Quad Core 9750 2.40GHz (Socket AM2)
Gigabyte GA-MA770-DS3 AMD 770 (Socket AM2) PCI-Express DDR2 Motherboard
OCZ 4GB (2x2GB) PC2-8500C5 1066MHz Reaper HPC Edition Dual Channel DDR2
Microsoft Windows Vista Ultimate 64-Bit Edition DVD
Blue Storm II 500 Watt Power Supply Unit

Old:
PCI-Express Sapphire ATI Radeon X1900XT
2x Maxtor DiamondMax 10 sata disks
DVD/CD combo drive

Right,
For a week now i've been trying to understand why my new machine keeps rebooting itself at similar intervals while installing the operating system.

When you boot it first thing in the day Vista will install for about 10-15 minutes before rebooting itself. After it reboots it lasts for less time until finally it reboots continually after the initial black vista load/install screen.

At first i thought it was my old Hiper R type 580 Watt power supply and thought it was knackered. So i bought the new 500 watt supply and it failed at all the same points.

I have been through the process of building the machine several times. There are no loose screws or anything that i can see that might short circuit it.

I only have what's above plugged in, i'm not even plugging in the Case fans yet. It seems to be a hardware issue in my opinion.

What has the effect of rebooting your system like that? Could it be the RAM's voltage settings? I've not checked that yet. Could it be the graphics card since its always after the initial load screen it reboots when the colourful vista install options appear.

Anyway if anyone has had a similar experience i would appreciate some advice as throwing myself out of the top floor office window is looking more and more appealing!

(1) Try just 1 stick(2 GB) of RAM and see what happens.
(2) Look in the BIOS to see if you are in IDE mode or AHCI mode.

- check the BIOS version, you need F4 (or better) for your CPU.

- check your RAM settings & make sure the voltage is set to 2.1v. It may be defaulting to 1.8v.

- check the CPU temp in the BIOS to make sure it isn't overheating.

- test the RAM with memtest86 or memtest86+ before installing the OS.

http://www.memtest.org/

"And that's the fishing line, because Sharkboy said so!"

I'm thinking of bad RAM...but also, it could be the Phenom core bug. I'm not sure if they fixed it with the newer ones, but it tends to have caused problems over some users.

Oh, try a different drive...in case yours are bad.

"it could be the Phenom core bug. I'm not sure if they fixed it with the newer ones"

Phenoms with "50" in the model number supposedly have the L3 bug fixed.

"And that's the fishing line, because Sharkboy said so!"

Thanks for all your replies.

I changed the voltage to the specified 2.1v and thought i'd nailed it - problem sorted. However the same problem kept happening. So i downloaded the new F4 bios version and managed to update it through Q-flash. Now even worse over the past 12 hours the machine cycles up on a high fan setting and just blows hot air from what i can see. No boot screen nothing. Tryed unplugging the PSU cable etc and left it for 8 hours and tryed again with no luck.

So i'm afraid testing the memory is out of the question at the moment until i can get the thing to restart.

I fear the worst is that the bios did not complete successfully however Q-flash said everything flashed properly - PASS infact. I exited Q-flash properly and i followed the manual to the T.

If anyone has anymore ideas great, otherwise thanks everyone for your help.