I now have had 3 CPUs (i7 7800X Skylake-X) that have died in an identical way in MSI x299 SLI PLUS motherboards.
The first one died while waking from sleep in windows. This was in October.
I had the replacement CPUs also die in a similar way, I woke them from windows while it was in S3 sleep and they also died.. fans turn and "00" was shown on the Debug LED with white LED light on, indicating cpu not detected.
When the first one died I changed both the CPU and motherboard.
No overclock, both on stock and default settings (with XMP on).
I am using 2 x 8GB RAM, this:
Corsair CMK16GX4M2B3000C15R Vengeance LPX 16 GB (2x8 GB) DDR4 3000 MHz C15 XMP 2.0 High Performance Desktop Memory Kit - Red
I have changed:
2 x PSU
2 x Motherboard MSI SLI x299
3 x i7 CPUs
Operation wise the system was rock solid, no crashes and temperatures were good... max with 1hour Prime was 61c .
When you wake it from S3 sleep there's a 1 in 10 chance it will kill the CPU.
What could be the problem ? I'm frustrated with these boards now.
I've got in contact with Intel and and waiting for MSI to get in touch.