# A New Benchmark Index: The PDW or Performance-Dollar-Watts

The global financial crisis has changed the way we buy hardware: there will be less frivolous, less impulsive and less irrational buying. And when purchases are made, they will be more value-based. Based on this observation, Jon Peddie has written a new equation to find the best hardware according three factors:

• 1 – Performance: we want the best possible performance
• 2 – Price: we want to pay the smallest price
• 3 – Power consumption: we want the smallest power consumption possible (less heat, less energy wasted…)

These three parameters are combined to give the PDW or Performance-Dollar-Watts index. The higher the index, the better the buying.

Okay let’s see some real numbers. I did a test with the upcoming FurMark, and one and two GeForce GTS 250. The price of each card is around 150 euros or 193\$US.

Here are the numbers (where VA is for Volt-Ampere, a way to measure the power consumption, and the only watt-related unity my wattmeter gives…):

• System idle: 188 VA
• FurMark with one GeForce GTS 250: 314 VA and 3623 points
• FurMark with two GeForce GTS 250 SLI: 435 VA and 7201 points

So if we put these numbers in Jon’s equation we get:

• Index1 (single GeForce) = 3623/193 * (1/314) = 0.0597
• Index2 (SLI GeForce) = 7201/386 * (1/435) = 0.0428

From this new index, the best choice is to buy a single GeForce…

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## 5 thoughts on “A New Benchmark Index: The PDW or Performance-Dollar-Watts”

1. SimTex

Would be interesting to apply this to e.g. Toms gfx card database, or something similar with a lot of cards. Although some weight factors probably would be needed for most users, since i double that many people weigh the power consumption that much.

2. bravura

I just want to say that the money payed for electric bill is as good as the money payed for the card.

3. ziple

Je pense que les VA c’est des watts parce que si je ressort mes formules d’électrodynamique de base on dit que P = U . I (P en watts, U en volts, I en ampères).

4. JeGX Post Author

yes ziple, VA est effectivement une unité de puissance, plus précisement la puissance apparente car elle est le résulat de la simple multiplication entre la tension et l’intensité. La puissance apparente s’exprime en VA à contrario de la puissance réelle (ou efficace) qui s’exprime en W (watts). En régle generale la puissance apparente est toujours supérieure à la puissance efficace et dans notre cas cette valeur est suffisante pour fixer les idées.