Almost plug-and-play — as long as you replace all sticks.

Yes, but with one big caveat: swap every stick at once. Do not mix ECC and non-ECC DIMMs in the same system. Supermicro boards will usually refuse to boot, or boot with errors.

The actual effort is: power down, pull the old sticks, pop in the new ones, power up. Most Supermicro boards auto-detect ECC and enable it. You might need to poke into the BIOS and flip a setting (usually under Advanced > Memory Configuration) if it doesn’t enable on its own. Worst case, clear CMOS, reboot, check again. No drivers, no soldering, no BIOS flash.

If you already have a mix of ECC and non-ECC lying around? Don’t bother. Buy a matched full set.

Don’t try to mix — your board will just refuse to play nice.