DS-7608NI-E2/8P/A firmware

Gold morning to all...

i have this NVR: DS-7608NI-E2/8P/A
with firmware: V3.4.0_151103, i can't send any email alert, and sometimes he reboots by himself!
before I had another NVR, the same but wihout /A with firmware V3.4.90_161080
I have 1 questions:
1) DS-7608NI-E2/8P/A or DS-7608NI-E2/8P (whout /A) can use the same firmware?
if yes i can download and install firmware: V3.4.90_161080?

Many tks.
Regards Alessandro.