Just in case nobody posted this yet regarding the random restarts/hangs due to the spikes

 I'm using AcBel R88 1100w and it's already 4 years old. I've been using it since the litecoin mining days of my 7950s and r9 290s.

Here are the things I did:
1. Distributed the load across the 12v rails. (If your gpu needs 2 PCIe Power connectors 8pin or 6pin.)
2. Added capacitors in the 12v PCIe power near the GPU. (I placed 3300uf 16v capacitors on the pcie cables near the PCIe connectors. I didn't need to splice the cable, I just tucked it in the back of the pcie cable making sure that it reaches the 12v(yellow) and negative wires(black).)
3. Clean the PSUs to reduce the temps to avoid triggering thermal protection.

If it stops the random restarts, good for you. It means that your PSU could actually handle the load. If it doesn't, then your PSU probably has other components that are at fault.

After doing these, I was able to eliminate the random restarts and it also allowed me to OC my GPUs again without problems.

YMMV.

Man, Your PSU is definitely NOT FOR MINING!
You should buy something that is at least 80+ Gold Certified.

My R9 290 never had any improvements since V7 I'm not sure why. It got stuck to 250-260Sols even at 1100/1300

About the random restart, My rig shuts down 15 mins - 1hr after miner starts and the bad thing about it is that my pc wouldn't restart by itself unless I discharge all the PSU capacitors (disconnect from wall sockets). Good thing about this is I fixed it by getting all settings back to stock and a little Undervolt. This minimized my gains when switching v8-v9 from 20% to 10%, but it's still a good improvement nonetheless. Never had any random crashes for almost 24hrs now.

My setup is composed of 2x RX470s (1200core,2000mem) 210 sols and an R9290 (950core,1250 mem) 250 sols My PSU is AcBel R88 1100Watts 80+ Silver.  My rig is almost half of that PSU's capacity, maybe it is really that bad.