1333 MHz RAM running at low speed

[Remixex]

Building an old PC i once had i noticed a problem, after i installed 64bit OS and everything, i went to the BIOS and it detects my RAM as 800 MHz with a config of 6-6-6-15, then when i try to change it in advanced configuration it won't let me go beyond 1066 MHz, the RAM is 1333 MHz running in single channel (only 1 RAM of 2Gb) i am also pretty sure my MOBO supports it, it is a DG41WV
What the hell is going on?
other specs=
CPU= Intel E5700
GPU= GT520
This mobo once worked in dual channel but now that i only use 1 stick the freq is not responding, it worries me because the BIOS doesn't detect it like it should and it once did
I ran CPU-Z, it says 400 MHz in dual memory, only confirming what i feared
I need help :/ (by the way i can test with another 2 Gb stick i have on my current PC, should i?)

 

[Remixex]

Nevermind...found it myself, in the box "1333 MHz will run as 1066 MHz" probably only works in dual channel, well whatever, have a nice day everyone who reads this and again excuse the double post idk what happened