Mosfets in full load could have 100C specially with high voltage at CPU and CPUNB. If you have CPUNB at default clocks or around, dont need 1.4V with CPUNB. This is only for high stability CPU and CPUNB clocks around 2600+ MHz. Its necessary cooling VRM with some cooling. Zambezi Bulldozers are with high voltages very power hungry (Vishera is better after OC, no need so much voltage for the same clock at CPU an CPUNB). Similar as i7-3960x after OC. Watterblock was only at CPU? If yes, its clear, with wattercooling setup you need always cooling VRMs (some 120mm fan or so). IF you have classic aircoller at CPU, with normal middle OC its good, because in most cases CPU cooler cooling VRMS a bit too (air flow direction).
LLC is better to set manualy (high). C5F and C5F-Z are different with real voltage and voltage in BIOS.

Guys, if you are overlcoking, in every case monitor the temperatures not only at CPU (in Coretemp max 65-70C! No more!), but power suply rails and VRM temperatures too.

No doubt .. after reviewing your 'My Computer Blog' .. and the above, that would be my 'guess'.
[[Can't touch it. Limited/Selected views. Haven't seen the 'mount' .. ect.)

(btw..generally..carpet and MB's don't play nice together..)

The only solice I can offer in this is .. the 'Third Time's a Charm'.
Nice 'My Computer Blog' -- you don't have more build pics do ya ??
Best of Luck.c.

Looks like the board is touching the radiator, could be shorting out? Voltage isn't the issue as I'v had my vCore up to 1.6v.

buy a bigger case or relocate the rad ..looks def like an heat retension /arcing issue but then you knew this or would'nt of trimmed the rad ..

it looks like in the picture you are only using the 4 pin cpu power plug if that is so you are putting way to much of a load on it you need to use the 8 pin cpu power plug too to even out the power.