I had a B450 board die this week, luckily I had a not-so-identical twin system with same which was idle. That said, I just sent the faulty board off under RMA to the vendor today. I specced up boards for Intel Precision Time Measurement (PTM) which is 1PPS over PCIe traces. New buys are typically B760M, aftermarket is B660M. Like with so many "interesting" Intel features, direct hardware qualification is necessary, as they don't list everything on ARK; anecdata can be checked against official datasheets. It looks like I want B660M with Alder Lake-S, 35W TDP, but passive coolers are out of budget, so I'd make do with stock. I already have an Intel I226V card with PTM, it's mostly about qualifying the motherboard. My J-series Celeron mini PC has <2W draw though according to RAPL and it's on timing duty in my home lab right now. Which is very very hard to beat. Even the GPSDO is low USB current draw; <150mA.