Re: DELL Precision T3600 UEFI Boot issue
It was a long story.
My T5600 suffer from more or less the same problem as yours before. Sometimes UEFI boot device no show, and cannot even add manually. Sometimes USB boot device detected but cannot boot (only a black screen) no matter by BIOS or UEFI mode. Really ignoring...
Until last Saturday I tried all possible BIOS version from A05 to A18, then finally located a change on A14 not only affect read request size on PCIe but also lead to USB boot problem as well. Details in this thread. After flash back to A13, everything's fine now.
Then I noticed to your post and checked that BIOS A14 for T3600 contains exactly the same enhancements. That's why I recommended a BIOS downgrade for you at the very beginning.