Another perspective on CPU value

As you might have already seen, the value section of our grand Athlon II vs. Core i3 showdown article includes performance-per-dollar graphs based on whole system prices. We began including these numbers some time ago at the behest of a readers who rightfully feel that, if they need to buy a whole PC to begin with, then processor pricing is only part of the equation. For example, if processor A costs $200 and only performs 50% better than processor B, which is priced at $100, then the prospect of paying double for 50% extra performance may not seem that worthwhile. In a $900 system, however, paying an extra $100 for 50% of extra performance suddenly becomes far more enticing.

We changed our full-system formula slightly this time, factoring in all the components you'd need to build a workable PC, including a case, power supply, and optical drive. Picking the right components proved to be somewhat of a challenge. In the end, we settled on parts we thought representative of a system your average enthusiast might buy: a new-ish motherboard with USB 3.0 connectivity, 4GB of RAM (or 6GB for the Core i7-900 config), a Radeon HD 5770 graphics card, a 640GB hard drive, a DVD burner, and a good quality case-and-power-supply bundle. Those parts pretty much correspond to the middle-of-the-road Utility Player build from our system guides.

What happens if you're not shopping for a middle-of-the-road system, though? What if you're on a tight budget and really have to cut corners? How do the performance-per-dollar CPU rankings end up looking then? We were curious to find out, so I fired up Excel, entered the low-end components below into our giant spreadsheet of doom, and watched the rankings rearrange themselves.

Platform Total price Motheboard Memory Common components
AMD 785G $410.90 Asus M4A785-M
2GB Kingston DDR3-1333
HIS Radeon HD 5670 512MB graphics card ($89.99), Western Digital Caviar Black 640GB hard drive ($74.99), Samsung SH-S223L DVD burner ($28.99), Antec Three Hundred with 430W PSU ($79.95)
Intel G43 $410.90 Asus P5G43T-M Pro
Intel H55 $420.90 Gigabyte GA-H55M-S2H
Intel X58 $545.90 Gigabyte GA-EX58-UD3R
3GB Crucial DDR3-1600

For our low-end component choices, I went with very affordable, micro-ATX motherboards with integrated graphics on all but the X58 platform. I stuck to 2-3GB of RAM, and I replaced our graphics card with a $90 Radeon HD 5670, since having a decent discrete GPU has uses beyond extreme gaming. Also, I opted for a cheaper case-and-PSU combo priced just under $80. All of this brings costs down quite significantly: minus the CPU, our AMD platform now costs around $411, down from almost $609 in our original set of numbers. Even the X58 platform has tumbled from $759 to $546.

And here are the results.

The points in our scatter plots follow almost the same pattern as in our big roundup, but all of a sudden, budget-friendly processors like quad-core Athlon IIs score much better in our performance-per-dollar rankings—no great surprise, perhaps. Interestingly, the Core i5-750 and Phenom II X4 965 remain neck-and-neck in the top two spots, albeit with their positions switched. It's tough to beat Intel's cheapest quad-core Nehalem, especially once you start taking power into the equation, as we're about to do.

Again, very little is new under the sun when it comes to our scatter plot. Looking over to our power-efficiency-per-dollar bar graph, we see the Core i3-530 and Core i5-750 have switched places, with the former now claiming the gold medal. The Athlon IIs have climbed up the rankings a little, but they still pale in comparison even to the old Core 2 Quad Q9400. AMD has higher load power consumption pretty much across the board, and no amount of fiddling with value numbers is going to change that.

I think we can draw two conclusions from this little exercise. One, quad-core Athlon IIs are very clearly the best deals if you're building a low-end rig and don't care too much about power efficiency. Two, even in a low-end rig, Intel's Core i5-750 still delivers by far the best mix of performance per dollar and power efficiency per dollar, at least among the processors in our test suite. If you can afford to plunk down $200 on a CPU, you can't go wrong with it.

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