I have run "standard" HD for years, without any issues. If I buy new drives, I get WD Purple drives and my home machine has a pair of WD Purple. However, I have a remote machine with standard HDs which has been running for about 8 years 24/7, and is still going strong. This thread had me check the fragmentation of my HDs. I have two Purple video drives, one at 79% fragmented, the other at 99%. All of the stats I have posted in this thread are from this machine with the video drives running at 79%/99% fragmentation. My boot & program drive is an SSD.
While your 2.5" drives aren't helping anything, I don't think they are the primary issue. I think you have another issue.