That code's related to a CPU issue, 100%. Here's some things you can try doing (with caution, of course):

Check the CPU power connection: Ensure that the CPU power cable is securely plugged into the motherboard. It usually requires an 8-pin or 4+4-pin connector near the CPU socket.

Reset the CPU: Remove the CPU from the socket, clean any thermal paste residue from the CPU and cooler, and reseat the CPU back into the socket. Make sure it is properly aligned and the socket lever is securely closed.

Inspect the CPU socket: Carefully examine the CPU socket for any bent or damaged pins. Even a single bent pin can cause issues. If you find any bent pins, you may need to carefully straighten them using a mechanical pencil or a specialized tool designed for this purpose.

Clear CMOS: Reset the motherboard's CMOS settings by either using the clear CMOS jumper on the motherboard or removing the CMOS battery for a few minutes. This will reset any BIOS settings that may be causing the problem.

Test with minimal components: Remove all unnecessary components from the motherboard, including RAM, graphics card, and any other expansion cards. Leave only the CPU and the essential power connections. Try booting the system with this minimal configuration to see if the issue persists.

Check for motherboard compatibility: Ensure that your Ryzen 7 3700X CPU is compatible with your motherboard. Refer to the motherboard's documentation or website to confirm compatibility and check for any required BIOS updates.

If all of those fail, test with a known working CPU, if you can.

It doesn't matter, they both offer PCIe4.0 x4 which is far more bandwidth than you'll ever need given your use case. For programs/games, we're just talking about load times here and the step from sata to NVMe is barely existent, so it's not going to matter much anyways.