Selection of right RAM for memory upgrade

[LightParticle]

Hello. I want to upgrade RAM on my HP Pavillion G7 2003-er notebook.

I find out that my mobo have 2 slots for a ram, but first one is occupied by 4GB DDR3 from Huyndai Electronics with frequency 800 MHz.

I have 3 simple question about upgrading

1.Do I need RAM only from Huyndai Electronics to add RAM?
2. Do I need only DDR3 for upgrade?
3. Do I need only 800MHz RAM or I can buy RAM with higher frequency?

And If answer of some of this questions is NO, I mean some of RAM specification will be not the equal
as RAM which is already installed, then I have some claryfing one question.

Is it will affect the performance in a bad way?

[banhien · Accepted solution]

@LightParticle 

My simple answers

1. You can use RAM from other vendors BUT to get full benefit of dual channel architectyre, people say use SAME existing RAM,
2. Since your machine uses DDR3 now, it is much better to use DDR3 to get RAM to run SAME voltage. You can also use DDR3L but this runs at lower voltage.
3. It is actually 1600MHz (800MHz is 1/2 of 1600MHz). You can use 1 step higher (such as 1866MHz) but it will only run at 1600MHz

Since RAM sticks are very cheap now, my suggestion is to get FULL benefit of dual channel and performance, please use the following fully compatible new set

            https://www.crucial.com/usa/en/pavilion-g7-2003er/CT3435539

Regards.