Hello, I have an Asus M4A-78 Pro mother board and a AMD black box edition Phenom II X4 955 processor and American mega trends bios revision 1501 which is the latest for that mother board. The mother board is rated to run DDR2 1066Mhz as well as 1200Mhz memory as well. The problem is that the Kingston hyper x memory will not run at the 1066 MHz specs and will only run stable at 800 MHz under prime95 loads. They are 2x2GB sticks and I have tested two sets of this ram with no luck at there suggested settings. 5-5-5-15-24 at 2.2 and 2.3 volts Ganged or Un-Ganged modes. From what I have read I have not been the only person with this issue and any input would be great to correct the problem. My system is very well cooled and temps run well below normal even under prime 95 and it is the second system I have built that has had the same problem with this manufacture of DDR2 1066Mhz ram not running at 1066 speeds....