@kithrup I can do you a Dell Precision T1650 tower. It's the generation before the 9020, but can take ECC RAM which is fully working in coreboot.
(it's also working in coreboot on Haswell, but needs a blob called the MRC; we have native raminit which replaces the MRC but the native init doesn't support ECC yet - but on ivybridge, which the T1650 uses, the native raminit supports ECC)