What is the beep code when you plug in the power cable?
I'm not aware of any "Intel recommanded" PSU. Instead, there is a Tested chassis list. All Intel chassis in the list have two 8-pin CPU power outs.
The clue here is that the system ran for 40 minutes.
That makes it unliky any kind of "normal" assembly error.
My first suspect would be a therimal issue after 40 minutes run time
How many fan are in you system?
Is the CPu using a active fan?
The blue chassis locator LED is controlled by the board BMC which should "boot" as soon as AC is applied.
The LED is controlled via a front panel push button or IPMI commands.
If it is on and staying on either the BMC is not booting (5v stand by issue? or FW?)
or maybe a incorrectly wired front pannel connector? Try unplugging all the front pannel wires an see ir the blue LED goes off.
also you should see the status LED flash amber and stop on green after about 45 seconds.
Power supply FXXRIGT670WPSU is the replacement spare for the Intel chassis.
I would check the PS you have to see what the output is on the 5v standbu, and other rails.
Thank you for thinking this through and your reply was helpful insofar as I was able to understand that my non-intel chassis was the next swapout component in my troubleshooting procedure.
So after ten weeks vacation in the clean mountain air recuperating from my setback with this machine build, I ordered an Intel SC5600Base chassis and rebuilt using the S5520HC (server board) Xeon E5620 (CPU) and tested memory, hard-drives and so forth.
The machine now works very well. Infact when I powered up, the Windows 2008 install resumed where it had left off in June.
So the thing was that after 40 minutes running OK, the OS installation had got to a certain point in the non-intel chassis, and then installed or configured some component/driver or whatever and effectively exposed an incompatibility between the S5520 and the (wrong) chassis.
So I hope that this information is useful folks; don't try to use non-tested chassis with your intel server board! In particular the chassis needs to come with a set of bumpers as specified in the quick start guide, and have the correct front panel connector configuration.