Motherboard bus speed and processors

I believe the ram will underclock itself to 800 and even with overclocking it wont be at 1066

Just answered another question just like this. The FSB they mention in the ad is actually not really a front side bus.

AMD systems have a reference clock that runs at 200Mhz and all the other bus speeds are derived from this using various multipliers. (200 Mhz X 15 Multi= 3.0 Ghz processor speed)

I believe the 2600 speed you are referring to is actually a hypertransport.

But stated simply you shouldn't have a problem. If you have an am3 processor, you can run the ram at the speeds suggested. If you buy 1066 Mhz ram, the motherboard should default to that speed. It doesn't have anything to do with what the other busses may be running at.

Yes, it is the hypertransport bus, which is the bus the processor communicates with the memory over. Thus, there is no need for trying to push the front side bus higher, like Intel has had to do. Intel CPU's, prior to i7, must communicate with memory over the FSB. That is why you see Intel processors advertised with "1333mhz" FSB buss speeds. Although they too are using a multiplier too get this number. 1333mhz is really 333mhz x4. A note here to everyone who is/was/did buy memory faster than 800mhz DDR2 for an Intel PC, notice that even with a "rated" bus of 1333mhz, the actual FSB the memory must communicate over is only 333mhz. So 800mhz memory, which is really 400mhz x2 (double pumped or DDR) is already rated for faster speeds than the data can move over the FSB. Faster memory than 800mhz on Intel systems prior to i7 has very, very little gain. You want 800mhz memory with the tightest timings you can find for the best all around performance.
The i7 is the first Intel CPU to make use a "hypertransport type" of bus like AMD uses, so the CPU has a direct faster and wider link directly to the memory.

AMD's hypertransport bus means it could make better use of faster memory, as does the new i7 systems.

I am NOT saying anything AMD has done is better or worse than anything Intel has done, just noting in general terms, without getting too envolved, how some of the stuff works.