I was thinking of upgrading my laptop to 16GB of RAM. It has 4 slots for RAM, and only one is occupied with a single 8GB DDR. I've heard that you always need to buy matched RAM, but it would be nice if I could just buy another single 8GB stick instead of buying a whole 16GB. I wanted to get some opinions from the folks here if it's really that important to buy matched RAM, or if I could use the info CPU-Z provides to get something "close enough".

IIRC, the only reason to buy RAM kits is so that you get dual/triple/quad channel operation which is faster, but seeing as you don't really see much difference with RAM speed and the resulting performance, maybe the "loss" of a dual-channel kit won't be too noticeable? Just wondering out loud; I've always bought RAM kits.

I’ve done it before years ago IIRC, but I was going in blind at the time. Like 2003 or so. More mismatched than that, the new stick was handicapped by the old. LOL
Now, IMO, stay with what you have or do it right and find an exact manufacturer match somewhere or buy all new within your mobo specs. I think current mobo’s would be more tolerant, but I would still be hesitant. I know that can be difficult or oddly expensive to match an old stick, but you might find a reputable seller on ebay. Those prices don’t look bad though. It *might* be ok, but nowadays I wouldn’t want to test on a crucial laptop.
You probably aren’t even using 8GB are you? I doubt you’d see a noticeable improvement like you would back in the day unless this a gaming laptop or used for intense work?
Do the specs on the mobo support this being an opportunity for a significant upgrade?

Haven't looked into the mobo specs, so I'll have to do that.

This is my gaming laptop. I'm currently watching what's happening with DCS 2.5 and trying to decide if I should double my RAM to 16GB. Right now the F-15C instant action maxes out my RAM usage. DCS says there may be a fix for that, so I'm still waiting to see what happens.

Please no more DCS discussion in this thread!

You may want more than 16GB for that All it takes is a new excuse to "fix" any issues, edit the minimum requirements text, and then put the onus on the customer to improve their hardware, so might as well spring for a 128GB RAM stick or kit and get it over with

All joking aside, what sim or game pushes the limits of 16GB RAM? IMHO, do not spend money to compensate for a poorly optimized software. Paradaz has 32GB on what I assume to be a desktop gaming PC and he's having issues so it would really suck if you'd spend on upgrading to 16GB and still see DCS eat up all of it due to poor code.

As to what RK said, I guess if you buy a 2133MHz stick to go with your 3600MHz stick, then the faster one will operate at the slower one's pace, but again, can someone really see/feel the difference between a 2133MHz RAM stick vs. a 3600MHz ram stick?

Just be very careful with those flimsy laptop memory clips, at least my last laptop had them and,

Yep I broke it trying to put a new stick in.

Saw this the other night, relevant to the situation. Don't be fooled by the title.