Issue sounds like "thermal Trip". Make sure you have connected the heat sink proper with some thermal paste(cooling paste)
hopefully issue should resolved after AC cycle.
What's the beep code? Below are the beep codes documented in TPS:
1-5-2-1 CPU: Empty slot / Population error CPU sockets are populated incorrectly – CPU1 must be populated before CPU2.
1-5-4-2 Power fault: DC power unexpectedly lost (power good dropout). Power unit – power unit failure offset.
1-5-4-4 Power control fault (power good assertion timeout). Power unit – soft power control failure offset.
Can you start with the minimum configuration - 1 CPU, 1 DIMM and 1 graphics card?
Firstly, Thank you for the responses.
As suggested, I have tried with only one CPU, RAM, Display Card. This did not solve the problem. I tried various combinations of RAM, CPU, and GFX card.
If I have only a single CPU installed, I get two faint beeps.
I am still concerened that the board starts immediately when power is supplied, i.e. I don't even get a chance to push the power switch.