It is possible you already have a 3.5 caddy (blue one in lower right cage) in your pc.  maybe a 3.5 hdd is missing? [IMAGE]   if yes you can save that for 3.5 hdd here is a caddy that contains a 2.5 adapter for ssd. you mount a 2.5” ssd on the black 3.5 to 2.5 adapter using up to 4 screws. [IMAGE]  
hey guys, i am once, once again looking for advice on my computer. i got it and it says "Alert! No Hard Drive Found" so i ran some diagnostic tests and came to the conclusion that my computer didn't come with a hard drive. so i am asking for anyone who can help me find one that is cheap, good, and that is compatible with this computer. thanks everyone.
best and cheap hard drives for a dell optiplex 3020 MT