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I'm using a Pentium 4 laptop (an IBM T42) as a home server, mainly to ssh to my home network from outside. Most of the time the machine is idle. If I got a new "Nettop", with an Atom D525, for example, would it use less power if both are left on 24/7? If so, how long do you think it would pay for itself, $300 - $350, in power consumption?

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closed as too localized by slhck, Hello71, Diogo, Nifle, Mokubai Sep 26 '11 at 21:09

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Pentium 4 processors have a max TDP of about 50W to 115W. This does not include the power consumption of the rest of chipset, such as the memory controller and graphics. The Atom D525 is rated at 13W, which does include the on-chip memory controller and integrated graphics. Although the Pentium 4 might outperform an Atom in some benchmarks, especially with single-threaded workloads, the Atom has been architected to minimise power consumption - particularly when idle (see graphs at bottom). The laptop's power supply is also likely to be less efficient than newer devices.

Regardless of the exact Pentium 4 model you have, an Atom-based computer will probably be more power efficient as a server. As a rule of thumb, electricity in the UK costs about £1 a year for 1W of power used 24 hours a day. (Obviously the cost could vary significantly depending on time and place.) So, a difference of 50W would mean you would break-even after about four years, assuming 1GBP = 1.5USD.

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He actually has a Pentium M, which is much more efficient than a Pentium 4. – paradroid Sep 25 '11 at 21:24
@paradroid Ah, if that's the case then the overall power consumption will be much closer for each option. The only way to know for sure if it's economical in the long run would be to measure the power with a Kill-a-Watt (or similar) and compare that with reviews of an Atom D525 system. – sblair Sep 26 '11 at 0:18

The ThinkPad T42 was a premium notebook which never came with a Pentium 4 or Pentium 4-M option. It was only available with the more expensive Pentium M (Banias and Dothan), which was an evolution of the Pentium III-M, avoiding the terrible NetBurst architecture. They were much more efficient and cooler running. The Pentium-M was developed into the Core and later the Core 2 Duo and so on, and NetBurst and the Pentium 4 were abandoned.

I know this is not an answer, but it was too long for a comment, and these facts would change the answer you are looking for considerably.

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not to mention smaller. P4M laptops were laughably humongous – Journeyman Geek Sep 26 '11 at 0:07

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