Celeron G5905 does not support ECC.

No. Intel only supports ECC on its Xeon and some i3 (non-F) models. The G5905 is a consumer chip with no ECC support regardless of what the chipset says.

The chipset might technically allow ECC signaling, but the CPU’s memory controller simply ignores it. You’ll boot with ECC sticks but they’ll run in non-ECC mode. No error correction happening.

If you need ECC for a home server, look at a used Xeon E-2224 or an AMD Ryzen PRO (or non-PRO Ryzen on certain boards). But for a simple Celeron box? Just use regular RAM and don’t worry about it unless you’re doing ZFS with scrubs that actually need it.

Save the ECC money for a bigger SSD.