Old laptop upgrading memory problem

[bonapartn]

I have an LG R590(-U.ARW1BT) laptop which is 7 years old now, and I want to upgrade memory.

It has Intel Core i3 350M and I looked on intel website, this cpu support 8gb ram. My laptop has 2x2gb ADATA DDR3 1066 ram on it.
I bought 2x4gb HI-LEVEL DDR3 1066 but when I installed both 4gb ram on it, laptop won't boot.
I am using new 4gb ram + old 2gb ram now. But why 8gb won't work. What am I missing and how can I use both modules?

Both ADATA and HI-LEVEL have 204 pins and PC3-8500(I don't know what is that mean.)

 

[algorithmbreaker]

PC3-8500 is 1066MHz. Try installing the other 4GB only, maybe the other 4GB stick is bad.

 

[bonapartn]

PC3-8500 is 1066MHz. Try installing the other 4GB only, maybe the other 4GB stick is bad.

Thank you for explanation. I tried this, and yeah one of new ram didn't working. Thank you for solution, too.