I recently had to replace the Power Supply Unit in a mid-range Dell PC, which was bought brand new for 790 EUR just over a year ago. The machine was just a month out of warranty. I could not believe my eyes when I saw a 265 watt PSU inside. Even 10-12 years ago I was putting nothing lower than a 380 watt PSU in machines. I was disgusted with Dell as I was the one who had specced the machine for this buyer and I had made sure to spec it a little higher than the run-of-the-mill machines they sell for 400-500 EUR. So that's where they're saving their few cents? Needless to say it was hugely embarrassing for me because I had recommended Dell to the buyer.

I'll make sure to remember this next time I go ordering new machines for people. I won't be ordering from Dell any longer, that's for sure.

A mid-range Intel Haswell machine with Intel HD graphics doesn't even need more than a 150 W PSU.

The retail market for consumer PSUs favors big numbers, so stuff has to be labeled "500 W". But as an OEM, you have way more options for custom designs. You won't believe what Apple uses to power their iMacs.

Greetings
The way this thread is turning is a very good one because we really can't just go by size or gut instinct. In most cases it really is necessary to add up the draws of major components to see the actual draw and for both ends of the spectrum.

I have an old Compaq Presario case Mini ATX that someone gave me that is so ugly it's cool (looks a bit like a batman mask with a bulbous chin) and it makes s superb Lan Part box except for on haunting worry. The thing doesn't put the power supply in any of the ordinary shelves. It's on a swing arm, suspended from the "bridge" that usually has the Optical at one end and a real PS at the other. Seriously this PS is no bigger in size than one I recall from a Tandy 8086. Oddly the lil' racal powers everything I throw at it up to an including 2 hdds and a DVD burner, 2 extra fans plus an old Alpha Novatech HS/Fan, max ram and 1.4 Ghz Celeron OC'd to 1.78 GHz Celeron. It just feels like it should implode but it is an Energizer Bunny.

Conversely I am awaiting the UPS man "as we speak" who is bring me a 450 watt video card and a 900 Watt Corsair PS. I can hardly type from anticipation LOL

Would you share some real-world (kill-o-watt) energy consumption numbers? Especially at idle?

Not kill a watt numbers, slightly better-

http://www.xbitlabs.com/articles/cpu...0_7.html#sect0

http://www.xbitlabs.com/articles/cpu..._11.html#sect0

Both tests done with a GTX 680 video card, pulling it for the intel video would save a few watts.

But I'd still go up to at least 200+ watts, probably 250-300 watts for a 'haswell' i5 or i7.

About 60 watts at idle.

First let us define, what we're talking about:

- 80PLUS Gold PSU (connected to 220-240 V AC)
- standard socket 1150 mainboard
- standard Intel Haswell CPU (i3/i5/i7) including Intel HD GPU
- two standard DIMMs
- one hard drive / SSD
- one ODD
- no add-on cards
- no overclocking involved

Usual figure for this configuration is around 25 watts idle, it can be optimized down to 10 watts (you need a capable PSU for that). For most CPU models numbers under load won't even go beyond 100 W for the complete system.

Wow, that is less than my old K6-III+ mobo at idle.

Please explain!

Link to your source?

I've seen 25watt idle figures for i7 4770s, like here-

http://hexus.net/tech/reviews/cpu/56...aswell/?page=9

i7-4770 @ 23 watts idle with a GTX 780 installed? I do not believe that test.

Xbitlabs, who do some of the best power consumption tests I've seen, have the 'haswell' i5-4430 idling @ 41 watts, no video card or optical drive. Other tests seem to agree with those figures-

http://www.guru3d.com/articles_pages...review,11.html

You need a PSU which is capable of operating efficent below the 20 % load range. Additionally your PSU must be capable to operate below 20 W at all. Not many are, this why the new Intel Haswell power-saving features are disabled by default.

Well, there are some requirements: 220-240 V AC voltage (so in 127 V countries you're out of luck, Hexus is from the UK), a certified 80PLUS Gold or Platinum PSU, which additionally operates efficient below 30 W, and ... Windows. Because with Linux - which is lacking in advanced power management - you most likely will not reach those low numbers.

My five years old AMD box gives similar results. The AMD 770 chipset consumes 20 W for itself, the (broken by design) CPU isn't able to enter the C1E state, so it stays at 15 W idle and the age-old nVidia card chooses to burn 35 W while displaying the desktop. But that is a thing of the past.

A Haswell CPU can idle below 1 W (and confuse voltage converters/PSUs by that), current-gen PCIe GPUs can reach 5 W with display turned off. SSDs go below 0.1 W (while SATA hard drives stay at 3-8 W active idle).

Note: If you do anything with "overclocking", then say goodbye to all that power saving efficiency.