Sentential said:
^^ Well for starters, your CPU cannot support Dual-channel RAM. It will run with multiple sticks of RAM, but it will never be in dual-channel. *Only* Socket939 Athlon64 CPUs and Pentium4s fully support dual-channel RAM. So for you its a moot point. Unless you plan on going socket 939 get a single 512MB stick of RAM.
Now thats not really true. Whether a system can run dual channel is really a function of the memory controller in the chipset. With Pentium 4's and Athlon XP's this has nothing what-so-ever to do with the processor architecture. The processor architecture does however influece how much benefit it gives.
A Pentium 4 paired with a chipset that only has a single channel memory controller will only sive you single channel access with 2x sticks of RAM.
A Athlon XP paired with the regular run of the mill nForce2 chipset will only give you single channel memory access with 2x sticks of RAM.
A Pentium 4 paired with a current generation chipset with a dual channel memory controller will give you double channel memory access with 2x sticks of RAM. Exactly the same is true of the Athlon XP with a nForce2 Ultra.
So when it comes down to it, dual channel memory support with the Pentium 4 and Athlon XP really depends on which mainboard you decide to go with. Don't expect the same performance boost with an Athlon XP as the total bandwidth of the the FSB is only as great (max) as a single channel of PC3200 DDR SDRAM. Architectural differences also affect performance here.
With the Athlon 64 the memory controller is no longer in the chipset, but integrated into the CPU, cutting down on memory access latencies. Socket 754 processors have a single channel memory controller and Socket 939 processors have a dual channel memory controller.
That is why I don't agree with your above statement at all. If you're arguing that a Athlon XP doesn't
really support a dual channel config because it doesn't have an integrated memory controller, that doesn't hold water either. Neither does the Pentium 4!
The main reason why Pentium 4's benefit so much from a dual channel memory config is exactly the same reason why they perform better with a larger level 2 cache than Athlon XP's and Athlon 64's.
Due to the extremely long pipeline of the P4, there is a much greater chance for branch misprediction, and hence, often data stored in the L2 cache is not required and must be pulled from the main system RAM.
A Dual channel memory config allows the P4 to continue to operate more smoothly as it doesn't have to wait as often for data to be fed to it. This is also the reason why larger level 2 caches benefit the P4 so much and noth Athlon XP/64's. A detailed explanation of the Pentium 4 architecture can be found over at Ace's Hardware. I'd recommend you check it out here:
http://www.aceshardware.com/list.jsp?id=4