It's a balance, if you are happy running high VDIMM, VCCIO and VCCSA for 2400mhz and its stable then that's fine. If not then just back off a tad and you might notice temps drop dramatically as VCCSA & VCCIO are CPU voltages for the IMC. There's going to be hardly any performance impact and a greater probability of being closer to 100% stable by the nature of running less on the edge settings.
The core temp readings will be very accurate on these chips as you are close to TJmax.
Is the CPU overclocked?
If VCCSA and VCCIO are on AUTO you might find they are being over volted excessively at 2400mhz so set these manually. You might see temps drop if so.
Run a multitude of stress tests, I've had plenty of times where I can pass IBT and fail prime and the other way too. I tend to run prime95, x264 bench and games.
Let's see... the settings that are actually available for setting the voltage are:
CPU Core Voltage
CPU Cache Voltage
CPU System Agent Voltage Offset
CPU Analog I/O Voltage Offset
CPU Digital I/O Voltage Offset
CPU Input Voltage
DRAM Voltage
PCH VLX Voltage
PCH Core Voltage
DRAM CTRL REF Voltage
DRAM DATA REF Voltage on CHA
DRAM DATA REF Voltage on CHB
Only the DRAM voltage is set to 1.65V; everything else is auto.
Since I can't get it to boot at all, stably, at DDR3-2666 even with very loose timings (~CL16), I guess I'm at the edge of my RAM's potential. I'm now trying to see if I can actually just push in tighter timings.
I've run Prime95 for an hour and it seems to be stable. I think I'll probably leave it running overnight the next time around once I've arrived at a setting that seems Windows, IBT, and benchmark-stable. (Prime95 testing just takes its sweet time... no matter how you put it, 10 hours is very long.)