laptop - Which type of RAM do I need and where to find it?

I want to upgrade RAM in my laptop but I'm afraid I'll buy a wrong RAM. I currently have 4gb and I'm looking to upgrade to 8gb. The laptop has 2 slots for RAM and there's one free at the moment.

I took the RAM out and took a picture:

I never bough any additional RAM for a laptop before so I have no idea what I'm looking at. I heard that when you're upgrading RAM, you need to buy the exact same piece or else it won't work?

Please help me, I'd appreciate a link to the RAM I need to buy or a full name or something, I can't understand anything that's written on the picture above.

EDIT: I found three RAMs so far that are 4gb and 1333MHz. Would any of these 3 work with what I have right now? Link1, Link2, Link3

Answer

There are four things that really matter when buying RAM:

• ECC or not, and buffered (registered) or not? Since we're talking about a PC-class system and you don't know anything specific, chances are about 99.99% or better that you want plain consumer-class non-ECC RAM. If there was ECC RAM in that laptop, you'd almost certainly know about it.


• Speed? In your case the sticker actually answers this: it says 12800. So you want to buy PC12800 RAM.


• Connector? With a recent vintage laptop, chances are you want laptop SO-DIMMs. The way to be certain about which type memory you need, if you can't identify the memory module that is already installed, is to check the manual.


• Size? 4 GB, in your case.

Using different manufacturer and model RAM sticks in a setup normally won't cause a problem, however it might cause suboptimal performance because the BIOS decides to downclock the RAM. That said, RAM these days is so fast that you're unlikely to notice anyway, and the performance impact from doubling the amount of RAM is likely to overshadow any such effects.

The piece you found on eBay appears to be compatible, however the only way to be absolutely certain would be to either ask Samsung (or whoever else built your laptop), or to simply buy it, install it and see if it works. The 1333 and 1334 probably refer to the memory bus data rate, which for PC12800 RAM is 1333 and 1/3 megatransfers/second, so this difference can likely be attributed simply to rounding.