i'm looking for a 150-250 watt high-efficiency atx psu; trying to build a budget system as a home media server. <$50. anyone know of such an animal, or a good source for psus in general. seems like not a lot out there for low power applications, everything's way overkill for a system that currently is drawing 80watts max.

When I saw low power in the topic title I expected more along the lines of 30 - 40 watts. 80 watts is still pretty high, none of the PSUs I use on my MiniITX systems even go that high.

But keep in mind a PSU only draws as much energy as the machine is using. Even a 1 KW PSU would only consume 80 watts with your current system (minus efficiency losses). Looking on NewEgg, I see a number of 80%+ efficiency ~300 watt PSUs for under $50, so I'm not sure I see the problem here.

well, that is the total usage including the PSU. i guess "low power" is a relative term. it's still a dual-core processor (45w) on a full desktop system. the 8 year old system that it's replacing was drawing 130w at idle, 24/7. huge difference in power bills--enough that this system could be paid for in less than 2 years. what would make an even bigger difference would be if i could find a way to suspend-to-ram and have a wireless wake-on-lan function; but that doesn't seem to be an option.

well, the "minus efficiency losses" part is a huge factor. this system has a 500w psu in it now, drawing 70w even at idle. previously, it was drawing 50w with a 350w psu. i want the smallest psu that i can use--150w is really what i'm after. the quoted efficiency is the max efficiency, which isn't obtained at lower power consumption. so the problem is that newegg has nothing of <250w (absolute max that i want) with >80% efficiency that i can find. here's a pretty good article about the topic, with some nice graphs of efficiency v. power draw:
power supplies

Here are some notes from researching PSUs for a low electrical power and quiet computer ~2 years ago. Maybe some useful info still. No info on overall effiiency of external power brick and internal DC/DC controller though

The counterpoint to "correct PSU sizing" comes from very high efficiency power supplies with very flat power efficiency curves. The models in the Seasonic S12 series, for example, differ so little in efficiency at the same 65~300W power levels that there's no real power consumption cost in choosing a high power model even if it is going to be used at lower power levels. With a system that only needs a maximum of 200W, the power consumption using a S12-500 or a S12-330 is essentially the same. Aside from the initial cost difference, there's no operational cost due to lower efficiency at lower power levels. With such power supplies, it makes sense to buy higher power capacity than currently needed in anticipation of future component upgrades that will demand more power.

For PSU efficiency, maximize the 12 V load and minimize the 5V load.

80-PLUS standard (80+% efficiency PSUs) http://www.80plus.org/

We also want a unit that is energy efficient and quiet so our logical choice is the SeaSonic S12 II 380W. We have not found a combination in our roundup testing yet that would cause us to seek a higher wattage unit. SeaSonic's own S12 II 430W would be the next logical choice but we felt like spending another $25 in this case was not worth it. There are numerous other choices that can made in this sector with Corsair, Enermax, SPI, FSP, and Antec all having good quality power supplies in this range.

picoPSU 120 W: http://www.mini-box.com/s.nl/it.A/id...=8&category=13. Review: http://www.silentpcreview.com/article601-page1.html. Needs an external AC/12 V DC PSU such as http://www.edac.com.tw/products_open.asp?id=158

picoPSU 120 W kit is no good because included AC/DC adapter is only 60W! http://www.mini-box.com/picoPSU-120-...=8&category=13 220 W DELL brick for use with picoPSU? "AC ADAPTER 220W SX280", part number Y2515.

Power supply PCI plate from Mini-box http://www.mini-box.com/s.nl/it.A/id...=8&category=13

Wide input voltage (12 - 25 V) version http://www.mini-box.com/PicoPSU-120-...X-power-supply
P4 cable adapter http://www.mini-box.com/4-Pin-P4-Power-Cable

From thread http://www.silentpcreview.com/forums...hlight=picopsu "First came the picoPSU. Now there are bunch of similar PSUs - external power brick plus a small DC-DC board which goes inside the case. Perhaps it is time to have a sticky thread to keep track of them? (Even better would be a SPCR article.)

Here are some:
mini-box (http://www.mini-box.com/s.nl/sc.8/category.13/.f) produce:
picoPSU: about 5 variants, 60-120W. The board is very small and attaches directly to the 20 pin ATX power plug.
M1-ATX and M2-ATX (3 models, 90-140W): intended for small PCs in cars. These are a moderate-sized circuit board.
PW series (4 models, 60-200W, moderate sized circuit board directly attached to 20 pin ATX plug.)

mcubed (http://www.mcubed-store.com/catalog/index.php?cPath=3 ) sells*:
EF16: 165W,
EF28: 280W
The manufacturer appears to be 'hifiatx', but I can't access their website because it demands a too-recent version of Flash. As a result, I'm unclear on what the non-brick part of this looks like.

Nexus (http://www.nexustek.nl/psb-1000_dc_to_dc_board.htm) produce:
PSB-1000. 150W? (No output specified, but they sell a 150W brick to go with it.) Smallish board with cable to 20 pin ATX connector, 4 pin extender (for 24pin motherboards) and hard-drives".

Dell Optiplex SX260 / SX270 Power Supply - 3R160?

Difficulty getting a quality 220 V AC to ~12 V DC adapter is the big problem with picoPSU plus lack of cables.

SilentPCReview list of recommended PSUs http://www.silentpcreview.com/article699-page1.html

You might want to look at the pico psu:

Not as powerful as you are asking for but they are dead quiet.

Hi,

Too the OP, you need to configure for the max/peak load for the system not just idle. You would create a problem by not sizing properly. As others have stated you can setup with larger load capable PSU but why waste the $$. You can size and allow for marginal increases but realize your load will be restricted to how the original was sized.

If the you are looking for a unit that is special because of physical size requirements then you might look at mini/micro-atx or HTPC units. Some of the micro desktop units have specification that may meet your needs. Fan-less units could be used but that too depends on the sizing specification. Embed systems do use speciallized PSU that could meet your needs but again $$.

Be sure to size the needs of the whole system at peak for your system and peripherals. This will require you to look at the specifications for each manufactures power specifications for the sub system(s).

If you have access to a wattage peak meter which some local power companies make available to their customers in the U.S. You could measure the load needs to size a PSU. But this would require you to setup the machine in a known state with all subsystems in use. This would provide you with a ball park figure.

I prefer to size from known specifications then measure but I do have a full test bench of equipment.

I'll not brand recommend as this just opens another can of worms.

thanks to all for the help. some of the stuff i had seen before, but revisited (pico, 80 plus site). especially the info about the flat efficiency curves; typical psu's dramatically lose efficiency after a certain point. looks like the 80 plus certified stuff has to be 80% efficient even at a 20% load. SO...looks like i can't really go wrong as long as i choose an 80 plus psu (there are efficiency graphs/info for all of the 80 plus products on the 80 plus site--you can't find this info for most other psu's), even if it is oversized.
@onebuck: i'm using a kill-a-watt meter to measure my power consumption, so my peak consumption of 80 watts is including the psu itself--no way i'm getting much past 100w with an efficient psu.

the pico psu is intriguing, but seems like it's just a bit out there; i feel like there'd be a connection that i'd need that isn't supplied by pico. not to mention the efficiency doesn't include the (not included, under-powered) power brick. and it's pricey.
this looks like what i'll likely be going with.

ended up with an antec 380W 80 plus bronze certified. system now consumes 59w at idle, compared with 71w with the old psu. doesn't seem like much of a difference, but it's >15% improvement i guess. or a whopping $10/year savings if it's on 24/7. well, still pays for itself in 2-3 years.