Got new ram but it freezes my pc

[Hyz]

Guys can i help me 

I have a zeb g41 motherboard
Core 2 quad q8300
Transcend 4gb ram ddr3 1066MHz
120gb ssd 
Recently i bought another 2 gb ram ddr3 from hynix 1333Mhz
So i tried using both of them 
But my pc freezes randomly and makes a buzzing noise .
I have tried both ram separately and it works fine jst when i put them together do the pc freeze.

If u could help i would be very thankful