Thanks for posting.
Unless you are having problems with your computer, there's really no need to arbitrarily update the BIOS. But, if you must update the BIOS, you should do them in order. The current BIOS is A16.
You should be aware that Dell does not support the Centos 7 operating system, so updating the BIOS may produce unpredictible results.
Supported Operating Systems
Your Precision T7500 supports these operating systems:
Windows Vista, 32-bit
Windows 7, 64-bit
Windows Vista, 64-bit
Windows 7, 32-bit
Windows XP, 64-bit
Red Hat Ent Linux 5
Red Hat Enterprise Linux 6
Note regarding operating systems not listed above:
Dell may not support an operating system for various reasons, including discontinued support from the software vendor or lack of availability with certain products.
For more information about an unsupported platform or operating system, please contact the software vendor.