Memory upgrade compatibility issues

I have a late 2012 iMac 27’ desktop (EMC 2546). I tried upgrading my memory with 4 SK Hynix 8GB 2Rx8 PC3L 12800s (serial # HMTHMT41GS6AFR8A-PB). When I turned on my Mac I got the 5 beeps and black screen signal at startup, suggesting that I’ve got an issue with my memory modules. I read somewhere that iMac’s are real finicky about which modules it will accept. I tried to do some research on the internet and though I did expand my knowledge on memory modules, I still can’t tell if the ones I installed are compatible or not. The last thing I want to do is exchange these modules other ones only to find out that the problem is not a compatibility issue but something else, such as the motherboard. If there’s anyone out there that can help me with this issue, particularly on whether or not I’ve got the right modules for my Mac. Also, what else could be the problem if it’s not the modules.

Please help, thanks!

Sil