820-2784 wont turn on.. do I need CPU present for S4?

[protocold]

CPU is currently removed from a 820-2784 that wont turn on. S5 rails are present and I do see LED1 on.

However, P5VS3_EN is 0v, do I need to put back the CPU for it to turn on? Or can I continue to troubleshoot without the CPU?

The board arrived without heatsink and I dont have the heatsink mount so not sure how to mount the CPU

 

[2informaticos]

Some boards have a CPU detection pin on its socket.
Such pin is tied to ground when CPU is inserted.
If not, power on sequence is broken.