My problems with offset werent caused by the M4E, its caused by the 210x series bios upgrade on the P67 range. Once id updated my Pro to the 2103 bios it started to behave exactly the same as the Maximus had with offset enabled.

My guess is theyve updated the VID table for turbo ratios in some way, but its had a really profound effect on high multi offset clocking. Voltage is spiking WAY higher than it used to and its fluctuating wildly depending on how many cores are loaded. 1 core load voltage has dropped by a ton, 2 and 3 core voltage is significantly higher and 4 core voltage is doing some crazy spikes going on and off load (possibly related to the cores "loading up" and rapidly changing the vid request?).

To solve it on my Pro I had to completely start again with balancing additional turbo against +offset and LLC level. My previous stable on bios 1850 on the pro was +0.085v offset and 0.360 max add turbo voltage. This gave me 1.048-1.085 idle and 1.536-1.544v load on High LLC. The same settings after updating to 2103 gave 1.120 idle and up to 1.62v load - that was an OMGWTFBBQ moment, but the cpu seems unscathed. Its taken a long time to find a setting thats stable with load on 1, 2, 3 and 4 cores and not just 4 cores and idle. Every voltage range had to come down and LLC had to be tightened up to bring voltages closer to the vid request amount. I've ended up on +0.035v offset and +0.152 max add turbo with Very High LLC. This gives me a solid 1.048v idle and 1.528v to 1.552v load (most of the time its bang on 1.536 but it does wander a little at times now). Thats a big change and a lot of hours work just from a bios update - it was like starting again on a totally different board tbh.

I'll be moving the chip back into the M4E this weekend and trying again with offset applying what Ive learned from 2103 on the Pro to 2105 on the M4E. I've got an overnight prime95 to run before I know for sure im stable and then I can have a good crack at 2133mhz on the Pro.

I've got high hopes for the M4E again now, fingers crossed!