Failed to overclock?

[lsung1]

Why does it say "failed to overclock" when i put my ram speed to its capable 1333mhz.

currently i have it under-clocked to 1060mhz...
i have 1 kingston stick(4gb) and 1 other one (that i dont know) 2gb
totaling 6gb of ram

thanks in advance

 

[Tradesman1]

Mixing DRAM can be problematic, have a feeling the unknown stick may be 1066 or whatever, can you provide the model numbers of the sticks

 

[lsung1]

heres a CPUz screeny:

<a href="http://imgur.com/G551KlK"><img src="http://i.imgur.com/G551KlK.png" title="Hosted by imgur.com" /></a>

or heres the link(if you cant see): http://imgur.com/G551KlK,kpV1Esn

thers 2 images

 

[Tradesman1]

Those images are the Kingston stick, what the other

 

[lsung1]

it doesnt have a brand guesss

Edit: the 'unknown' ram came with my computer when i bought it