Re: The only safe PC is a SPARC
It appears that the best "open" CPU architecture is the decade-old SPARC T2 - the full Verilog source for the CPU is provided, and there is no "management engine."
Not so. The openpower bunch have done some interesting things, and you can buy an ATX motherboard with a POWER CPU that is completely open. That is the CPU design, board schematic, BIOS source code and much else besides is freely available. They use (I think) the words 'blobless computing', referring to the fact that the source code for every bit of software and firmware is available.
The best bit is that it offers competitive performance, and is a lowish price too.
Take a look at Raptor Engineering