I'm wanting to upgrade to 16GB of memory currently have 4 sticks of 2 which equal 8GB want to know can I just use 2,-8GB.

yes, you can do this. Just be sure to install them in the correct slots so you utilize the duel channel. refer to your mobo manual.

Yes you could, but you'll want to make sure that your motherboard and OS can support 16gb of RAM.

What is your computer specs? Also, Why do you need more ram? Are you doing any editing or just gaming? No point of getting additional memory if you are just gaming.

My go-to solution is http://www.crucial.com/ , and click on "Memory." There you can install a system scanner in your PC, which will tell you what memory upgrades the PC will accept. They also have an on-line scanner which will do the same thing. Either way, they are ad-ware free / malware free. Crucial used to be the OEM manufacturer for Dell memory, maybe they still are. I have purchased direct from them a half dozen times over the years, and their customer service is excellent. They've sold a couple of solid state drives with mediocre reviews, but their other million products are top notch.

Either way, once their assorted scanners tell you what your computer will accept (including every combination from smallest RAM total to largest), there's nothing to stop you from going to another vendor of your choice with that knowledge and get a RAM / kit on your own. Personally, I might pay an extra 5 or 10% to get the Crucial product, then and there.

I find it easiest to create an account on their website. They never spam, in fact they never send me email; the bastards. It's just that if you ever go back on their website to place another order, it saves you a couple of keystrokes if you sign in again.

Also, some older memory may be out-of-production and will be jaw-droppingly expensive, as supply dwindles. If that's the story with your memory, it's not so bad to go on eBay and save 85% on some used memory. I just wish the eBay vendors would claim to follow ESD (static electricity) procedures. RAM is pretty hardy, and Used is usually good as New. And you can save lots if your RAM is out of production. But if you buy used off of eBay, you have to know what you're purchasing, because there are subtle variations.

I have been known to order RAM from Crucial at the same time I order a computer, and sometimes the RAM arrives first. When the computer arrives later, I open it up, screw the warranty, take out the small-sized RAM that was included, and populate all the RAM sockets with the new RAM, maxing each socket with the largest sticks they'll accept. So every time I do that, all the sticks in the computer match; maybe having all matching RAM sticks avoids some problems, but it couldn't hoit.