If the motherboard BIOS in your machine is BIOS it is not capable of ever supporting UEFI. The newer cards support UEFI, like the GT 730. There are Hybrid cards by MSI and Shappire that support BIOS and UEFI via a swtich.
In reality what you have is an off-lease re-manufactured product that is circa fall 2012. The PSU is non-standard, and the 6300 is limited to low profile cards. You can not hang an ATX, it would not start-up without jumpering pins. Also, I am trying to remember the slot wattage. Something about it is only 35W.
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