Considering the beefy sinks on the VRMs for that board, I doubt that's the problem. I'd worry more about cooling the CPU better.
Undercover, the VRMs have nothing to do with keeping temps down.
I turned off all the thermal throttling measures for the CPU
, and still had clock throttling at 70C or so. Because the problem disappeared entirely when the VRM protection was disabled, I'm convinced that this is due to VRM overheating. My hand isn't a very good measure to go by, but when I touched the VRM heatsink, it was burning hot.