Hello. I want to add more RAM to my Dell laptop. I already have 4 GBs, and I want to add 4 GBs more. The RAM that I have is: M471B5173DB0-YK0 4GB 1Rx8 PC3L-12800S-11-12-B4 It is available here on Amazon for ~ 2K: https://www.amazon.in/samsung-PC3-12800-DDR3-1600MHz-Unbuffered-M471B5173DB0-YK0/dp/B00TTC60Q8 and: https://www.amazon.in/Samsung-original-204-pin-VOLTAGE-PC3L-12800S/dp/B00HZKKDNC But the Amazon one says "11-13-B4" while mine is "11-12-B4". So will this RAM be compatible with my computer? If I have one module of Samsung RAM, do I have to install another Samsung module only, or can it be of another company? Also, is it safe to buy RAM from online sites? I have previously taken out, cleaned and refitted the RAM on my desktop, so will it be the same method for the laptop as well, or should I take it to a computer shop? I have basic experience working with computers. Thanks.