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I'm looking to build myself a home ZFS fileserver with ECC memory.

The e3-1220L v3 has a TDP of 15 watts, compared to the e3-1230v3 with a TDP of 80 watts. These chips are, Of-course, both Haswell 22nm process. Performance wise the latter leaves the former for dead, while the former is deliberately targeted at low power tasks.

My question is - when idle - will there be significantly different power draw between the 2 cpu's? To frame the question another way - ignoring PSU inefficiencies - will there be a noticeable difference in overall power draw, assuming the tasks are not CPU bound?

Notes:

Here is a comparison of the CPU's at Intel Ark. The key differences are the number of cores (2 vs 4) and the Processor base frequency specified as 1.1GHz vs 3.3GHz (and associated turbo frequencies).

  • "...ignoring PSU inefficiencies" -- If you're going to ignore the PSU, then I can (by judicious selection of PSUs) make almost any processor appear to use less power at idle than another. IOW the less power the system uses at idle, then the selection of the PSU to maintain that efficiency becomes more crucial. "...when idle ... assuming the tasks are not CPU bound" -- You have a warped concept of what "idle" is. – sawdust Sep 18 '17 at 23:25
  • @sawdust - re PSU - I know if I get an efficient PSU tuned to handle 100 watts, it will use less power when drawing 100 watts then a similarly tuned/efficient PSU which is designed to handle the 200 watts the more powerful CPU requires - I am not wanting to muddy an answer with PSU concerns. You are right re bad wording of the question with respect of idle vs not CPU bound - I'm aware of the difference. – davidgo Sep 19 '17 at 0:12
  • "I know if I get an efficient PSU tuned to handle 100 watts, it will use less power when drawing 100 watts then [sic] a similarly tuned/efficient PSU which is designed to handle the 200 watts the more powerful CPU requires" -- You're not making any sense. You're also making claims about drawing full power, whereas I'm describing power draw at idle. Read superuser.com/questions/446419/… – sawdust Sep 19 '17 at 1:00
  • @sawdust - I think we are talking past each other. For the sake of this question, can we just pretend that the PSU is 100% efficient at all loads - so we can focus on the core of the question - will a chip with a lower TDP use noticeably less power then a faster chip of the same type with a higher TDP when its not taking advantage of the additional processing power ? – davidgo Sep 19 '17 at 7:02
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There will not be a significant difference in idle power usage - might even be identical. Get the „real“ CPU. The low TDP variants are for use cases when your cooling capabilities are severely constrained.

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The two processors have the same Haswell microarchitecture and idle at essentially the same power level. The low-power processor is there for server workloads that demand the lowest possible power consumption and do not require high performance. A typical use case for the E3-1220L v3 would be a ultra-compact, low-power NAS or web server where very small size, minimal fan noise, and low energy usage are required.

In your case, it's unlikely you're that constrained in terms of power usage or cooling. Go with the faster processor.

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