Why ram 800mhz not 1066MHz

hi
I installed corsair 1066MHz and heatsink for memory.But when i looked into my BIOS. It recognized the 1066MHz memory as 800MHz .what is wrong how to solve ?
thank you

If you are using multiple stick then try to use alternate.Shut down pc removed the old memory replaced it with the two new one restart if error in booting occurs, Shut down and removed both ram, replaced with one at a time, trying to boot up with one sticks at a time, resulting in the same issue as step 1.try with another one try that at the rated volts and speed.Maybe it is faulty ram.

That is why before upgrading always check your configuration and support this is the problem due to your motherboard is not supporting frequency over 800mhz..so you need to get down to 800mhz it will be better if you check configuration and possible then replace ram to 800mhz

Try to check ram with memtest86+ ,if they are faulty replace them other wise the motherboard does not support 1066Mhz another option can be try to add voltage and timings for ram so configure it until you get the desired result.