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I am running an Intel P4 prescott with HT on my home server (linux file server on encrypted disks on software-RAID5 and virtualisation host for three further machines). The performance for this purpose is really okay. When the system is idle it consumes about 140W power.

I am considering buying a new mainboard for an e.g., intel i3-2100T or an Intel i5-2390T. Both are low power CPUs with a TDP about 40W.

Has anyone experiences how much power a recent mainboard with one of these CPUs a 3-4 'green-energy' disks (6W each) consumes? Do I get underneath the 100W threshold?

What's about the performance of these low power CPUs? Are they comparable to an Intel P4 with HT?

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migrated from serverfault.com Jun 26 '11 at 14:59

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Are they comparable? No... It's not so much that they're in different leagues as the i3/i5/i7 range are at the top of the highest pro league while the P4 is still wondering what that ball-shaped thing does, anyway... –  RobM Jun 26 '11 at 14:08
    
but also the low-power i3 with 2.5GHz? –  Walter Zomb Jun 26 '11 at 14:11
    
@Walter - the lower power models can be just as fast as the non-lower power models. They're just tuned a little different so that they are more eager to use lower speedstep settings and won't use turbo boost for as long. –  Joel Coehoorn Jun 26 '11 at 14:16
    
Believe me, when they describe the i3 low power part as "low power", they were talking about its power consumption profile, not about how fast it can go relative to a Pentium IV. The i3/i5/i7 range are a very good example of how Intel had a good rethink about processor performance after the disappointment of the Pentium IV (which really wasn't a good part at all) and decided that chips that work "smarter" are a lot better than chips that compromise real performance in order to ramp up clock speed and hence give the appearance of working "harder". –  RobM Jun 26 '11 at 17:12

2 Answers 2

Performance-wise, they should blow that P4 out of the water. P4's just weren't that good. In fact, they were so bad that while they were in production AMD's chips of the time were actually a good bit faster, and Intel felt the need to re-brand their processors (thus, the "Core" brand was born).

The difference will be even more pronounced for your specific workload. You have a base system plus 3 VMs, or four machines in total. The P4 was a single core with hyper-threading (two logical cores, one of which is severely handicapped). The i3 is a dual core with hyper-threading (four logical cores, two of which are severely handicapped). The important thing is now you have enough logical cores to dedicate one full-time to each VM. That should make a huge difference in total performance on your system.

As for thermal performance, the chips are rated for 65 watts. Add 4 6 watt disks and you're looking at 90 watts, before you add anything for RAM, motherboard, video, optical disk, or add-on cards. I wouldn't count on meeting a 100 watt ceiling, but 150 or 200 watts sounds reasonable, depending on the draw of your other items. And speaking of those items, the new cpus you're talking about put most of the video adapter on the chip as well, so it includes what has traditionally been one of the larger power draws in that 65watt TDP.

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so you think, if I would take an i3-2100T which is rate with 35W (secure.wikimedia.org/wikipedia/en/wiki/…) and also includes the video chip, I can add the power consumption of the disks and get something about the total amount of power consumption? –  Walter Zomb Jun 26 '11 at 14:37
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they were so bad their LAPTOP chips blew them out of the water, actually. I was suprised when a 1.4 ghz pentium M outperformed a slightly faster pentium 4 –  Journeyman Geek Jun 26 '11 at 15:13
    
@Walter - I think I said the opposite - that you can't just add up the disk draw + cpu draw, because there are other components in your system as well. But you did remind me that the 2100T has a 35watt TDP rather than 65, and with that adjustment I think you do stand a decent chance of meeting a 100watt ceiling... if you're very careful with your other components. –  Joel Coehoorn Jun 26 '11 at 17:17

A P4 is such an old processor that anything you can find on the market today will be significantly faster.
No, really.
It's that old.

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