Multiplier and Front Side Bus (FSB)

The FSB affects everything connected to the bus, including the NorthBridge and RAM.  A higher FSB is preferable, and we have seen Intel release their last cpus with 1333FSB in the the Wolfdale family.  If you increase the FSB, the RAM will run at the faster speed.  The multiplier is set in the cpu, with some power-saving chips able to dynamically adjust it when the cpu is not being used (Intel's SpeedStep and AMD's Cool'N'Quiet).

The new Nehalem i7 cpus avoid the FSB completely and using a direct point-to-point architecture, intead of a bus.  QPI (Quick Path Interconnect) has a much higher bandwidth and takes advantage of faster DDR3 memory.

The multiplier is the clock rate that is generated in a CPU, using PLL-based frequency multiplier circuitry. In essence, the FSB clock rate is applied to the CPU and the frequency multiplier increases the internal clock rate of the CPU.
 The FSB really applies to the motherboard circuitry and the rate at which it transfers data, this is probably the area where overclocking is the most finicky because it involves all the components in a computer motherboard. Multipler overclocking only involves the CPU clock rate.
When overclocking, FSB is usually used because in can be increased incrementally. This allows for minute changes that are taking advantage of the clock rate overhead that most components have before they become electrically unstable.
(think of it as a safety factor to ensure stability)
Multipliers on the other hand increasing the Clock rate of the CPU substantially each increment it is increased.
a FSB of 200 x10 multiplier results in a CPU rate  of 2000 where a FSB 200 x11 multiplier is 2200.

You won't be able to push your FSB that high, because together with the multiplier, it determines your final cpu speed.  Most cpus won't overclock 50%, so if your current FSB is 200, 300 would be excessive, and you would have to make sure your PCI and PCIe buses stayed at 33MHz and 100MHz.  Here, someone was able to push their FSB to 350: http://img186.imageshack.us/i/1195025370xpatyinke971lxt0.png/

As I said before, a higher FSB will give you faster memory access - this has been a known fact since the Pentium was invented.

A FSB of 200mhz actually is running the equivalent of 800mhz as the data is being signaled on the rising and falling edges of the wave form of the electrical signal as well as at two intermediate points between them. I essence 4 bits of data per clock cycle also known as quad data rate.

Gory detail http://en.wikipedia.org/wiki/Front-side_bus

This depends on what CPU you have and what FSB it requires to get to its proper clock rate. Not all will allow a change in the multiplier which is why FSB overclocking became popular.
Since this is an AMD CPU motherboard with hyper transport, the system should actually allow separation of the FSB and memory bus rates in order to acquire the proper rates for each on there own.
You have to remember that upping the FSB effects the other bus rates for the PCI and PCIe slots. This can have a great effect on the components installed on those slots. The PCIe does have a setting in BIOS to change the clock rate but not the PCI slots.
All in all, when your BIOS is set to the  AUTO positions, the system should recognize the components correctly and set the correct clock rates. Perhaps by manually setting these attributes you are handcuffing  the system from applying these proper settings.