I have a Gigabyte GA-81K1100 motherboard. It has dual channel memory which is working but it should be showing 3 gbs of memory and is only showing 2. (I have 6- 512 DDR's installed)

Here are the instructions that came with the motherboard:
GA-8IK1100 supports Dual Channel Technology. When Dual Channel Technology is activated, the bandwidth of memory bus will be double the original the fastest speed at 6.4GB/S DDR400. GA-8IK1100 includes six DIMM slots, and each Channel has 3 DIMMs as following:
» Channel A: DIMM 1,2, 3
» Channel B : DIMM 4, 5, 6
Below are the explanations:(I only put in what was applicable to my situation)

5. if six DDR memory modules are installed: To activate the Dual Channel Technology and to make the size of each DDR memory module detected, please use six DDR memory modules with identical size and type and insert them into the six DIMMs following the sequence below. DIMM 1: Double or Single Side DIMM 2: Single Side DIMM 3: Single Side DIMM 4: Double or Single Side (if DIMM1 is inserted a double-side module, then DI1MM4 must also be inserted a double-side one.) DIMM 5; Single Side DIMM 6; Single Side


That is what I did and I am sure they are in right, the DIMM number 3 and 6 are the ones that aren't showing.

I’ve looked through the bios and there is nothing there that I can see that might need to be changed.

I'm wondering if the problem could be my CPU as that's the only thing I haven't upgraded (a salesman recommended against it saying it would only improve my performance about 5%) My current processor is a 1.73 gb Pentium 4, could it be that it can’t handle the extra memory?

This is what it Gigabyte says about the CPU: Supports 800MHz FSB Intel® Pentium® 4 Processor with HT Technology-Leveraging the Intel® 875P chipset to support 3GHz+ P4 CPUs on 800MHz FSB, Intel Hyper-Threading Technology and advanced features, the GA-8IK1100 delivers a full-value, highest performance solution for today's most demanding tasks.

If the problem is the CPU, how can I be sure I get the right one? And if it’s not would a new processor be a good idea anyways?

Thanks