I had one 4 socket IBM server with Xeon processors and it ran off one power supply (sort of). Don't know about the HP system but my IBM pulled about 6.0 to 7.0 amps during normal processing. If the temps got high and the fans revved up close to full speed it would pull almost 10 amps. I couldn't afford the power to run it. I'm sure these later HP systems are more power efficient but they will still pull a lot of power. Do you have enough amperage headroom to add that system? If it is a 4 socket 10 core system then it will probably run 40 threads. 8GB might be a little small. You could probably run some of the vina WUs but definitely not MIP1. 40 VINAs would probably be about 2 to 3 GB. I am running a couple of HP DL380 G8s with dual socket 8 core processors on one power supply and they pull about 3.3 amps each. It will probably run on one power supply as they are intended to be redundant if one goes out but at times you may be pushing it close to the limit.

You're right, I completely missed the dedicated circuit and the hyperthreading. 32GB would probably be plenty of memory. My 32 thread machines run about 5.5GB with a mixture of MIP1 and OET. I would make it a 20 amp circuit. 12 amps is the recommended maximum running 24/7/365 on a 15 amp circuit. The 14 gauge wire would be running quite warm. I installed two 20 amp circuits just for extra safety and piece of mind.