T21 stock firmware errors out on APW12, so you would need aftermarket firmware to run after swapping PSU from APW11 to APW12. For the fully assembled 'T21 transformer' we just ship with vnish on stock AMLOGIC control board. We have tested this build with both ePIC UMC and MARA UCB and it works with both, but they do add some additional cost to the build.
Both these CB options are nice since they have zero dev fees , so will likely pay themselves off over time.
But if you're looking to save on upfront cost, you can just flash luxos or vnish on the stock AML CB and it works fine.
Now if your T21 came with a CV1835 control board, that changes the math, since there is very few firmware option available. In this case, your best bet is to just remove the stock CB and replace with epic or MARA.
Yeah I had the cv1835.
I ORDERED and received some epic boards for the two t21 units coming this month.
I rave on about epic boards as I have found them to work better than any board I ever used.
I will end up needing 3 covers to prevent shorts. The electric resistant duct tape is sloppy looking.
I have a ton of psu's from my s19s.
I hope to end up with 4 or 5 miners once I sell off all my other gear.
One L7
THREE MODDED t21's
Maybe a gpu rig.
Oh two nano 3's
This would do about 14kwatts an hour.