Anti-ME anti-UEFI anti-backdoor CPU

Why do you want to run existing software in a different CPU? Why not fork your software and port it to the different CPU?

older processors have vulns because they just didn't have sophisticated security.

Those graphs clearly show that IPC is no longer improving in a significant way. A 0.4% improvement is not worth upgrading for.

system management mode is the backdoor
side channels and debug ports
debug ports and system management mode like functions
Debug ports
If you want to avoid hardware backdoors then avoid x86 and ARM based proccessors of any age. If you want to avoid software based backdoors you best use anything pre core2 duo x86 and anything pre ARMv7 for ARM. If you want secure hardware, it doesn't exist.

Those improvements add up, as you'll notice the first graph shows a 20% cumulative improvement from the ancient Core 2 chips you're talking about to modern ones, and the second graph shows the improvements can be several times greater yet for some applications. That's all without counting other improvements included in newer CPUs, like much more aggressive clocking thanks to process shrinks and better dynamic clocking, bigger caches, and faster system buses (particularly for RAM).

Such old x86 chips are so slow, you'd get better performance emulating it on a modern tablet SoC.

If you are going to upgrade to anything botnetted go to the intel haswell generation. As it is the last proccessor before the un-removeable version of ME and graphics blobs for intel gpu's. Haswell added more execution units to the proccessor for more throroughput.

Oh gosh, people can do nasty things when they have physical access to the machine!

Broadwell is fine too, (((Librem))) laptops are based on Broadwell chips that run free graphic drivers.

No need to get that old.

You can get a AM3+ FX-8370e, these are the 90w under volted processors, specially binned for it. They are the best of the process and will overclock to about 4.4/4.6 Ghz on air and will reach 5GHz on water. Much better than the FX-9590 which is shit because it will not go 5GHz on all four cores because of its settings, the 8370e will. This will make run like the faster I5 from April this year, so still pretty good.

You can get the last fastest BIOS motherboard the GA-990FXA-UD3/UD5/UD7 with the lower revisions 1.0/1.1/1.2. They basically have all of the modern connectors present except for for M.2 support. But add about 4 Samsung 850 Pro's/Evo's in raid 0 and you will have M.2 speed with 2 GB/s read and write. hould not be to expensive now.

Then get 1866 DDR3 with the lowest CAS of 8 or 9. These have the best true latency and perform better than 2400 DDR with higher CAS that have shittier latency as well. The FX processors work better with 1866.

You can add any modern latest video card in SLI etc.

This will be a very fast system that can still play all modern games at good settings.

Get GA-990FXA, they still have BIOS, FX-83** do not have PSP