I recently purchased a Dell Inspiron 620 desktop. It came with a Core i5 processor and 6gb of ram in two slots, one with 4gb and the other with 2gb. Dell only recommends 8gb of ram maximum (2slots x 4gb). I was told by a tech at a computer store that you can in fact install 16gb of ram (2slots x 8gb) and be fine. If this is true, then what is the "downside" to this upgrade and why does Dell limit the ram as such? I mainly use my computer for Lightroom 4 and Photoshop CS6 for photo editing. Thanks!
Well, in the past when you max out ram, the ram speeds slow down. It really depends on the motherboard of that computer and since it's a Dell, they come with cheap motherboards that are limited in every way.
I really don't deal off the shelf PCs that much, but from experience, if Dell says only 8GB, then only 8GB will work efficiently. The motherboard may even be picking about ram. But if you want to try it out, put in the same speed and voltage ram that came with it.