The chances of you having an infection that survives a reformat is remote, since only a firmware infection has that capability, and the chances of you having one of those is extremely remote.
But on the extremely unlikely chance that you do, then flashing your BIOS would have removed it.
So if you truly do have a Remote Access Trojan, then it is not on your computer, and you should look to any external devices as the source of your problem. I recommend you start by resetting your router.
If your computer is synced to an online account, this could also be the cause of your problem, as if another device you own has been compromised, your computer will get re-infected as soon as it syncs with the other device.
In any case, if you have done as you say, and have reformatted and re-installed your OS, and then re-flashed your BIOS, and are still having problems, then this is not something that can be resolved remotely through a forum like this, and I recommend you seek hands-on assistance.
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