What RAM is compactible by specifications?

[haspeix]

Hello,

My mobo is ASRock G41C-GS. Now I have 4GB RAM (KINGSTON KVR1333D3N9/4G).
I want to put 4GB's more.
So, at what RAM specifications should I look, that my PC worked as effective as possible?
Can you link me some sticks?

Thank you for your answers.

P.S. I can not find, where to buy the same stick.

 

[Tradesman1]

I'd look at the GSkill NT series of value DRAM they use the low density ICs you'll need for a 775 mobo - here's a single

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231421

also come in 2 stick packages

 

[haspeix]

Thanks mate

 

[Tradesman1]

No worries