Dell T7500 ram failure: finding and buying replacement...

Computer:

Dell T7500, 2012, Single Riser (6 slots)

Current RAM
Hynix (Koreo 07) ram, (6 cards) 8GB 2Rx4 PC3L - 10600R - 9 - 11 - E2

Problem:

Had to put my computer (I work as a freelance film, sound, and photography editor) into climate controlled storage for over a year due to life complications and when I finally had the opportunity to set it back up this summer it started giving me issues and eventually started giving me a bluescreen. After much research and troubleshooting between myself and a local computer repair shop to confirm, it was determined that one of my ram cards had failed and needed to be replaced. The problem has been in finding a replacement for the failed card or even all 6 cards. I am knowledgeable in computers but am no expert and occasionally get tripped up, so I am looking for help.

I have gone over the manual and know it is important to have the same brand and type of ram, evenly populated to have a balanced, well running machine. Unfortunately I cannot find the exact same card as what I have, so have looked for cards as similar as possible and for cards that meet manual specs for the T7500 in other brands with the intention of possibly replacing all 6 cards. Online I have found that Timetec has SK Hynix cards and am wondering if one of these cards would be compatible with the remaining (5) cards I currently have since they are Hynix based. Additionally, a Timetec rep responded to me asking about one of their cards and recommended I purchase a: 16GB 2Rx4 PC3L - 12800R -11 -13 -E2. It being a 16GB I assume I would need at least 2 to balance slot population (16-16-8-8-8-8), but it is the memory speed that has me thrown. According to the manual, which I know is as old as the computer, the T7500 only supports 10600 or 8500. So will this Timetec card even work in my system or with my old 10600 cards?

The local computer repair shop is understaffed and busy replacing broken phone screens (quick and easy money for them) so they are no help. My computer expert who originally helped me buy this computer and build it up for my freelance work, was my brother who has since died in a car wreck. Looking for some help and/or advice in getting my computer back into shape.

Let me know if there is any additional information needed. I wasn't sure how detailed to get in this post.