Prices in this post are as of about mid-April when I bought the parts for my new computer except for the DDR2 SDRAM. Prices will be a bit lower now. The idea in the original purchase was to go with moderate components and then overclock them to the speed of more expensive components.
First the CPU:
Core 2 Duo E6600 @ 2.4 GHz $308 Overclocked to 3.125 GHz Core 2 Duo E6700 @ 2.66 GHz $512 Core 2 Duo E6800 @ 2.93 GHz $1200
The E6600 is the most popular Core 2 CPU Duo by far. It is by far the most cost-effective of the family--the E6700 cost 66% more with only 11% increased speed. All three chips are identical in structure, differing only in their factory speed ratings. So, an E6600 running at E6800 speeds is absolutely equivalent to the faster chip. As mentioned in a previous post, this becomes a simple issue of risk management. Not every E6600 may hit 3 GHz, or even 2.66 GHz, but user experience shows that it probably will.
Here the point isn't the increased GPU speed, but the increased capability of the GTX GPU over the GTS. The comparison requires some serious benchmarking like those at Tom's Hardware. For an overall boost of about 22% in performance without overclocking, the GTX runs a whopping 54% higher price on the street. Overclocking cuts the performance gain to just 14% or so. Unless you're a hardcore gamer with cutting edge visuals, the difference in price is very hard to justify.
Memory can be more problematic for overclocking. Buying faster memory than that for which your system requires can buy you some clearance to seriously overclock the CPU and have the memory keep up. I listed current prices for the DDR2 SDRAM because I don't have the original comparison prices handy.
OCZ 2 x 1 GB Rev 2 Platinum 800 MHz $150 Overclock to 870 MHz so far OCZ 2 x 1 GB Rev 2 Platinum 900 MHz $180
The savings here isn't as great now as it was when I first bought the SDRAM. Still, even today I'm getting the same performance for $30 less. I haven't fully explored the overclocking capability of the DDR2 SDRAM yet. I'm still hoping to get close to 1000 MHz, which would provide more dramatic savings over that more expensive SDRAM. This is the first time that I tried to overclock vice buying faster memory. The payoff in this build wasn't what I hoped for in this area. Prices continue to drop rapidly, so I may swap this memory out for faster ones in the future if they don't eventually overclock to at least 950 MHz.
Overall, Tanker Bob saved about $930 by overclocking these three individual components in a system which only cost $1290 including the case and miscellaneous parts--a 42% reduction in system price. Careful thought, lots of reading, and solid planning can provide great performance at a bargain price if you are willing to accept a little risk.