What's the most efficient PSU for a mid-low power computer?

Question

I noticed that almost all power supply units (PSU) nowadays come with an 80plus label. This means that over 80 % of the electricity I pay for in my bills will actually reach my hardware instead of being wasted in heat, and that my hard work saving on the decimals of Watt there will make sense. Great, but now how do I choose if I want a PSU for a computer which is not too power hungry?

Specific technical question: what's the most efficient PSU in a non-custom form factor, at a consumption of 100 W or 200 W, for an EU 230 V or 115 V home?

Hypothetical concrete question with probably too much detail (skip if you understood above): what's the most efficient PSU I can use for my new mini PC/slim PC/HTPC/whatever, AMD APU based, either

• chipset A88X, processor A8 or A10 family (Kaveri), socket FM2+, motherboard mini-ITX or micro-ATX (mATX);
• or socket AM1, Athlon 5350 (Kabini), motherboard mini-ITX;
• or socket FT3b (Beema, Mullins), anything;
• or socket FP4 mini-ITX motherboard for Carrizo or Carrizo-L, anything available (nothing for sale right now or in foreseeable future AFAIK)?

Answer 1

Since you mentioned EU 230V, I've tried to source from EU suppliers. The first OEM that sprang to mind was Seasonic. Indeed, there's the Seasonic X-400 Fanless 400W, 140,13 euros at Amazon.it. There's also the Titanium rated AX 1500i, but that's less efficent and way too costly.

However, monetarily, is it really worth it? Even a good quality PSU is unlikely to be used for more than 10 years. Let's round that up and assume it's on 24/7 for 88 thousand hours. A 80+ Gold unit is typically significantly cheaper than a Platinum unit of similar rating. For an approximately three watt difference in efficiency, that's about 264 kWh. It depends on your electricity price, but in most places, you won't even recoup your investment, and even if you do, you'd be better off buying a high-yield bond.

So, for cost, I'm going to recommend a 80+ Gold unit, the 350W Super Flower SF-350P14XE Golden Green (59,69 euros). Obviously, there are the environmentalists among us, though, would would be willing to save a few watts regardless of the cost (a commendable motive), for which the Seasonic offering would be the obvious pick.

I've switched over to Amazon.it, the original links form Amazon.de for the Platinum and Gold rated PSUs are here

Answer 2

The Seasonic Platinum series seems to be good.

The Seasonic site says it has a 92% power efficiency.

It's also fanless, so it's super quiet. However, it is very expensive for a 400W PSU. However this seems to be one of the most efficient, if that is what you are looking for.

Answer 3

For a thorough and safe compilation I went to the good old 80plus.org.

For now it seems the best at 100 W consumption are (those under 92 % struck), among the ATX at 500 W max or less and sorted by average:

• CFD KRPW-TI500W/94+ or Enhance ATX-1850: 93.89% (ATX12V, max 500 W, average 93.47%);
• Dell L240EPM-00: 92 % (SFF, max 240 W, average 92.45 %);
• Fujitsu S26113-E613-V70-: ~93 % (actually at 127 W; ATX12V, max 250 W, average 92.41 %);
• Sea Sonic SS-460FL or XTS 460 or LDLC-460FLP: 91 % (ATX12V, max 460 W, average 92.01 %);
• Dirac DIR-TCAXP-500: 92.32 % (ATX12V, max 500 W, average 91.64 %);
• Chengdu G500: 91.48 % (ATX12V, max 500 W, average 91.89 %);
• HKC T-500: 90.77 % (ATX12V, max 500 W, average 91.67 %);
• Sparkle Power SPI450ACAP or PT-450M or FSP450-60ETN: ~92 % (ATX12V, max 450 W, average 91.32 %);
• Avnet ADEPAD0300I-01: ~91 % (ATX12V, max 300 W, average 91.31 %);
• HP D12-240P2A: ~94 % (actually at 120 W; ATX12V, max 240 W, average 91.18 %);
• Antec EA-450 Platinum: ~91 % (actually at 90 W; ATX12V, max 450 W, average 91.18 %);
• Tiger Power TG12-0250-01: ~92 % (ATX12V, max 250 W, average 91.17 %);
• Scythe SPTRP-500(P)(N) or HPA-500PT-F14S (C): 90.47 % (ATX12V, max 500 W, average 91.06 %);
• Enermax EPM500AWT: 90.65 % (ATX12V, max 500 W, average 90.94 %).

I bolded those which were relatively easy to find. Some close relatives of the Sparkle and Tiger can be found at 80 $ or less; the others are typically around 100-120 $. The Enermax seems definitely not worth its price compared to the Antec and Sea Sonic, but it depends a lot on where you are. Finding the OEM ones would be the real success...

Lenovo also had some great results but these were with custom format factors. (Also some great results at 1U and 2U form factors: glad to see server farms are now paying attention, but off topic here.)

Full list of models above 92 % efficiency at 50 % power, of those with capacity up to 300 W: D12-240P2A; S26113-E613-V70-; CPB09-045C; D14-200P1A; D13-280P2A; DPS-300ADV; F180EPS-00; PS-4201-1HA; HKF1802-3A; F240EPM-00; IFX90ATX300W; PS-4281-1HA; TG12-0250-01; ADEPAD0300I-01.

Full list of models above 90 % efficiency at 20 % power, of those with capacity between 301 W and 500 W: KRPW-TI500W/94+; ATX-1850; FSP400-60AGTAA; PCC005-020H2; PCE009; DIR-TCAXP-500; KRPW-PT500W/92+ REV2.0; ATX-1350; PS-5401-1HA; FSP500-70ETN; PT-450M; SPI450ACAP; FSP450-60ETN; IP-P400IQ3-2; DPS-320QB A; DPS-320QB B; FSP400-60ETN; GW-6000(92+); EA-450 Platinum; FSP500-70AAPB; XTS 460; LDLC-460FLP; SS-460FL2; DPS-500AB-5 X; FSP400-40AGPAA; GPG400V; FSP450-60PTM; PCC005; EPM500AWT; SS-400FL2; X7 500; FSP500-50FSPT; XPSQ-450.R4; SPTRP-500(P)(N); HPA-500PT-F14S (C); IP-P500IQ3-2; GW-ATX400(92+); DPS-320RB A.

Answer 4

Personally I prefer the mini-ITX form factor, so I ended up choosing a mini-ITX A88X motherboard, with the A8-7600 AMD APU (65 W TDP).

Consequently, I chose the Antec ISK110 VESA case, with 90 W power adapter. Antec claims an efficiency up to 92 %. Given the case cost some 80 €, it's really impossible to beat on the cost side; as for efficiency, the Gold unit suggested by Alpha3031 is around 89 % so it's probably comparable. There is also a case with 150 W PSU but it makes no efficiency claims.

I've not found tests for such adapters, but Antec typically scores well enough in 80plus tests (see my other answer) so I don't think it would lie. The adapter is AcBel ADB002 and its external temperature is around 38 °C after several hours of (light) work.

This solution addresses the use case provided by my question, but arguably not the specific question I made, because it's for 90 W power and not 100 W. It's also not suitable for A10-7850K and other 95 TDP APUs without downclocking. So I guess Alpha3031's answer is the most reasonable for the general case and I'll accept it in few days unless you suggest me otherwise. :)