Which RAM should I buy to speedup my system

I am using an old system that is an Asus AIO PC. It is a very old system and I am looking to upgrade its hard drives from HDD https://www.allhdd.com/hitachi-hds722580vlsa80-hard-drive/ to SanDisk SSD Plus SATA III 2.5" Internal 120 GB - 2 TB SSD | Western Digital. But their sizes are different my old HDD size is larger than Sandisk SSD will I have to order another SSD or I can install it in my PC.

Hi @northstardefenseil,

Have you opened a Support Case? If not opened, for more information, please contact the SD Technical Support team for best assistance and troubleshooting:
https://kb.sandisk.com/app/ask

To clone your disk you must use one of the same size or larger. Some advanced systems allow you to choose which elements of the old drive you want to clone, but I don’t recommend it.