Originally Posted by OrionBG
You are possibly looking at the wrong temperatures. The VRMs on mine (and on all that I've seen here) are around 80C-90C under load (which is completely normal temps for a power draw of almost 370W). Mine is running at 4GHz with a monoblock and 3x 360mm rads.
There are no wrong temperatures when all 4 Mainboard sensors show < 50 C (Tdie included) during power virus loads, with temperature on VRM dominated by the fact that it's right *after* CPU in loop. All 4 motherboard sensors show around 40 C in that hard load. (This being HeavyLoad CPU + Furmark on fullscreen.)
I take it the hottest sensor is VRM, the others are near room temperature. I have the other VRMs and SOC also watered. And 4 ECC overclocked RAM sticks, Vega 64 and Vega FE overclocked GPUs and 2 M.4 SSDs. There's no component relying on passive cooling that emits any notable heat.
My cooling solution is a bit overkill to remove around 1.4 kW according to my power meter (during power virus loads), 1/3 from CPU, 2/3 from dual GPUs, quad D5 PWM pump at low RPM (60W), MORA 420 Pro with 4 Noctua A20 PWM fans.
VRM block is a custom cut piece of kit made from Watercool's Micro SW-X DIY block, attached with Thermal Grizzly Kryonaut and/or Alphacool Eisbach 11W/(m*K) pads where applicable. CPU likewise on Watercool Heatkiller x3 TR4 block. SOC is using generic Watercool mainboard block, secondary VRM and 10GbE are using some Watercool ASUS mainboard VRM block with hacky attachment. RAM blocks are 2x Alphacool's x4 block - only ones that work right with high sticks - and SSD blocks are by Bykski. 2 pumps run under a serial Alphacool Eisbecher Dual D5 top, 2 run inside serial EK X-TOP Dual. And there's an EK X-RES 3 300mm reservoir.
It's very easy to get trapped air in a monoblock that's at the top of your loop. My recommendation is to flow water bottom up and if pressure is low, reorder loop so that hot components and only them are before radiator, everything else on return path. (Yes, I've put a lot of work into that huge experimental loop.) Flowing water top down tends to flow over bubbles regardless of pressures.
Seriously, I got your temperatures with unfanned originally heatsinked VRMs on my Fatal1ty. Fan right above dropped them to somewhere near 70 C. That's with old overclock similar to yours (flat 4.1 GHz at 1.4V as opposed to letting PBO do magic) - mine is higher now, the low temperatures allow lower voltage and PBO tuning from P3.30 allows really high boost clocks. (I've seen 5.1 GHz when it was 4 core load.)