DDR3 RAM not detected?

A couple of years ago I bought a Lenovo G50 laptop, with two RAM slots and one Samsung 4GB DDR3 RAM. Recently I decided to upgrade its RAM by buying another 4GB DDR3 RAM for the free slot. But when I placed the new one alone, the laptop didn't boot. You could hear the computer working but the screen was black, the lights of Num Lock didn't show and after a few seconds the computer powered off. These are the same symptoms I experienced when I tried starting the laptop with no RAM, so I figured out the computer didn't recognize the new RAM. Then I inserted both of them and the computer started normally, but the Properties panel only showed 4GB. The old RAM is a Samsung at 1600 Mb/s and the new one is a Kingston at 1333 Mb/s, but I did some research and all I found out was that there's no problem in mixing these two speeds. Finally, I also updated the BIOS and nothing new happened.

The old RAM is a Samsung M471B5173DB0-YK0.
The new RAM is a Kingston KVR13S9S8/4.

Guillermo

If it didn't work with the new RAM then it is probably dead. Get it replaced.

Edit

Ah, made the assumption that the OP would have used the Kingston find your memory tool to select the appropriate memory for his machine.

flyingtiggeruk

Ok so I believe the new ram is 1.5volt. (See source links for more info.)
Whereas the old one is compatible with 1.35 LOW voltage ram.
See my Lenovo link, with a discussion of someone having similar issues. It came down to the voltage of the ram.

If you do not believe this to be the issue, try the new ram by itself and not with the old one. See if the 4gb stick shows up by itself.
Otherwise if it DOES work, then perhaps you have a bad memory slot. Or dirty contacts for the other slot.

MrWakeup