I have an ancient DDR3 Xeon that doesn't support any AVX (dual x5690 and 96GB 1333 MHz RAM). You reckon it would even build / run at all?

CPU (2012)

  Model name: Intel(R) Xeon(R) CPU E3-1265L V2 @ 2.50GHz

  Product Name: P8Z77 WS

  05:00.0 VGA compatible controller: NVIDIA Corporation AD106 [GeForce RTX 4060 Ti 16GB] (rev a1)
  05:00.1 Audio device: NVIDIA Corporation AD106M High Definition Audio Controller (rev a1)

This works.

Loading will take some minutes, but at 96 you can squeeze the model in and have some headroom around like ~10 GB, although depending on the Xeon, you may have to downgrade to E4B instead. Should still work thou.

It may work - depending on your ram speeds it might not even be that much slower.