Power Supply Unit

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The PSU, or Power Supply Unit, is responsible for converting the (AC) mains power received from the wall socket into various DC voltages used by the components of a PC.

Computer systems need a good clean energy source. When purchasing a $3000 dollar top of the range system most people neglect to also put those extra bucks into a decent reliable energy source for their system. No longer is the $20 'yumcha' PSU that comes with a $60 case sufficient, as they are noisy and unreliable (often dying after a year or two's use, taking out components with them), but more importantly are unsuited to powering modern computers due to a weak 12V rail, and don't have the right connectors (24pin atx, pcie, sata etc).


Contents

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Introduction

Disclaimer: This information is just a collection of user comments. Any decisions you make from the following is your choice alone.

Basically a good rule of thumb to follow when purchasing your next PSU is to look at how much the unit costs, and the PSU brand. If you're buying a case with a '480W' PSU included for under $60 then you're almost guaranteed a problematic, and possibly dead, system. Money wise, look at spending at least $70 for a cheap reliable brand name PSU (see below) for some basic overclocking, with strong 12V rail(s). If you are getting into some more serious OC and running SLI you would probably want to invest some more money (probably in the range of $150+) and time into researching what you need.

For more information on why GENERIC power supply brands are not good, see the SPCR PSU guide and X-bit labs PSU guide, as well as jonnyGURU for an example of a PSU not handling its 'rated' loads (500w powmax psu blows up before its even loaded up to 300w)

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What To Look For

Name brands (see below) are usually the best indicator of quality/reliability. Also look at the individual rail specifications to check they are suited for your computer. For newer (any motherboard with ATX12V/P4 4pin connector) computers, the 12V rail specifications (how much capacity they have, measured in 'amps') are the most important. The capacity of the 5V and 3.3V rails are very important for old P3/Athlon XP systems (ones without ATX12V/P4 4pin connector), and just about irrelevant for newer systems (This is because P3/Athlon XP motherboards power the CPU off the 5V rail, while newer motherboards power the CPU off the 12V rail, so in a newer system, there are no big power users on the 5V/3.3V rail at all, only the 12V rail). Use the PSU calculator below to work how big a PSU (wattage and 12V amps) you need.

PSU Wattage and 12V Calculator
(in beta)

Multiple 12V rails explained:
With ATX12V 2.0 and later, 2 or more 12V rails was introduced to comply with safety regulations (no more than 20A / 240W on any one user accessible wire). The way this is done in every PSU except for a couple of very high end PSU's such as Enermax Galaxy 1kw is that there is still only one 12V power source, which is then split in two or more 'rails' via current limiters (typically set to around 18-20A, even if PSU label says its less). This means that when comparing multi 12V rail PSU's, the combined 12V rating (in amps) is what matters, and how many 12V rails there are. The individual 12V rail capacities are basically irrelevant unless the PSU label says it has more than 20A available on an individual 12V rail. Also since the only thing that makes them 'split' is current limiters (which do nothing unless they are tripped), there is really NO stability / overclocking advantage in having dual or more 12V rails compared to an equivalent single 12V rail PSU. SilentPCReview explains further.

How to work out the 12V combined amps:

Most newer PSU's should have a wattage listed just below the 12V1 and 12V2 current 'ratings'. For example the antec neo HE 430w, the specs shown in the picture below, has 12V1+12V2+12V3=48A. but look below that in the specs table and the 12V combined rating is 384w, or 32A (384/12=32 - amps is watts / voltage and the voltage is 12V in this case). If the PSU you are looking at doesn't have this information, theres a guide on getting an estimate of total 12V amps from the 'how they work - a more detailed look' section. Alternatively some PSU's list this in the manual, or below the main rail ratings on the PSU label.
Image:AntecNeoHe430w.png

High end SLI/Crossfire (x1800xt/x1900xt/7950GX2/8800GTS/8800GTX etc) users make sure you grab a single or triple/quad 12V rail PSU as its been found that most dual 12V rail PSU's won't work at all in such systems.
See the ExtremeTech's article. The dual 12V rail psu's on test, and the Silverstone 650w ZEUS (older revision - problem fixed in the new revision) all shut off with crossfire as they were running both PCIE graphics cards off one 12V rail (both the motherboard power and power through pcie connectors), which caused the PSU to shut down when 20A current limiter was tripped. In the Zeus 650w case a workaround of using a molex-pcie connector can move one of the graphics cards to 12V4 (instead of 12V3), but this can't be done on a dual rail psu, since only the 4pin ATX12V is wired to 12V2 (everything else on 12V1). Some newer dual 12V rail PSU's are just a single 12V rail (such as Antec Earthwatts 500w), or have current limiters set to > 20A, so research before buying. The PSU calculator above has tests to predict whether your system will have issues with dual 12V rail PSU's.

Also look for a PSU that has the connectors that your computer needs. For example newer PCs (most of athlon64 939, P4 775) want 24 pin (or 20+4) PSU's, so don't buy an older (20pin) PSU for them. If your buying a psu for a 20pin motherboard it's often a good idea to buy a 20+4pin PSU so you can use it when you upgrade in the future. Also higher end PCIE graphics cards (eg 7800gt, X800XT) use PCIE power connectors, which many PSU's don't have, so check that your PSU has a PCIE connector (or two in the case of SLI - adapters can be used, but not ideal).

Once you know what basic sort of PSU you need and are looking at individual models, its best to read up on some reviews beforehand. Unfortunately most of the power supply reviewers on the web know very little about PSU's (so often make misguided conclusions and common mistake errors such as using BIOS/software for voltage readings), and often use inappropriate test systems (such as testing an SLI capable PSU on a light, single videocard system). Instead it's better to look for reviewers who load test the PSU to its maximum ratings (or at least test the PSU on a system more powerful than yours) and have a good knowledge of the technical workings of a PSU, such as X-bit labs, jonnyGURU, HardOCP and Silent PC Review. Also be alert for incompatibilities, for example many high efficiency PSU'S (such as Antec Neo HE series, Seasonic S12 500w / 600w - fixed in latest revision for both), have notable minimum load requirements, so are not suitable for very light systems with certain motherboards. The section on 'important PSU issues with popular brands' below has more details on this.

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Recomended Power Supplies

Note: this is far from an exhaustive list, but more just PSU's that offer top value for money. To work out which category you need first use the psu and watts 12V calculator and then choose a psu in a category at or above whats recommended.

Important: some manafacturers (such as DFI) mandatate a minimum psu spec regardless for their particular motherboard/graphics card etc. So even if the psu calculator puts you well in the clear for say a 400w psu, they may refuse to give technical support because you didn't meet their minimum '500w' or '550w' spec.

Disclaimer: Any change of details for any of the listed power supplies by the manufacturer is not our fault as the details of the listed power supplies are correct at time of posting. This list of power supplies only provides very basic details of each power supply. If you need further information or more in-depth details of a certain power supply or power supplies then you have to research it yourself. In general, this list just provides a very basic comparison between the power supplies.

Posting Note: In future anyone adding recommend PSU's please set out details of power supply in the same format as the ones below, thanks.

ATi/nVidia Links:

Note: for the PCIE connectors listing '6' refers to standard 6 pin pcie connectors, '8' refers to the new 8 pin pcie connectors that some high end cards use. In 99% of cases the 8pin connectors can have 2 pins unclipped to be used as a 6pin pcie connector if required.


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Bargain power supplys (under $80)

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe 6/8 Other Features Review Price
Antec Earthwatts EA 380 380w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 27A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 1/0 Overclockers ~$66
Antec Basiq BP 350 350w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 23A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 1/0 ~$40
Coolermaster eXtreme Power RS-430-PCAR 430w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 29A Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 1/0 jonnyGURU ~$46
Coolermaster eXtreme Power RS-460-PMSR-A3 460w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 29A Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 1/0 Replaces RS-430 hardwaresecrets ~$55
Silverstone Strider ST350 350w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 25A Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 0 Replaces ST365 ~$47
Zalman ZM360B-APS 360w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 26A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 Hardware Secrets ~$68
Vantec ION2 450W 450w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 30A Image:Tick.png Image:Cross.png Image:Cross.png Image:Tick.png 1/1 Not that quiet ~$55
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Enthusiast (Under $120)

400w or greater, 28A or greater on 12V rails combined, 1 PCIe connector

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe6/8 Other Features Review Price
Antec TruePower Trio TP3 430 430w Image:Tick.png Image:Tick.png Image:Tick.png 29A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 1/0 ~$85
Antec Earthwatts EA 430 430w Image:Tick.png Image:Tick.png Image:Cross.png 30A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 1/0 SPCR ~$80
Antec Earthwatts EA 500 500w Image:Tick.png Image:Cross.png Image:Cross.png 34A Image:Tick.png Image:Cross.png Image:Tick.png Image:Cross.png 2/0 Actually single 12v rail jonnyGURU, Hardwaresecrets ~$99
Antec Earthwatts EA 500D 500w Image:Tick.png Image:Tick.png Image:Cross.png 34A Image:Tick.png Image:Tick.png Image:Tick.png Image:Cross.png 2/0 replaces EA-500 ~$99
Coolermaster iGreen RS-500-ASAA 500w Image:Tick.png Image:Tick.png Image:Tick.png 33A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 Driverheaven, BigBruin ~$116
Corsair VX Series VX450W 450w Image:Tick.png Image:Cross.png Image:Cross.png 33A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 1/0 jonnyGURU, SPCR ~$89
Enermax Modu82+ 525 525w Image:Tick.png Image:Tick.png Image:Tick.png 40A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/3! Extreme silence Anandtech ~$115
Seasonic S12 II 430w PSR430 430w Image:Tick.png Image:Tick.png Image:Cross.png 30A Image:Tick.png Image:Cross.png Image:Tick.png Image:Cross.png 2/0 SPCR ~$95
SilverStone Element ST50EF Plus 500W Image:Tick.png Image:Tick.png Image:Cross.png 35A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 jonnyGURU, SPCR ~$95
SilverStone Strider ST56F 560W Image:Tick.png Image:Tick.png Image:Cross.png 36A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 SPCR ~$107
Zalman ZM460B-APS 460w Image:Tick.png Image:Tick.png Image:Cross.png 34A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 X-bit labs, SPCR, Driverheaven ~$105
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Value high end (under $180)

500w or greater, 35A or greater on the 12V rail(s) combined, 2 PCIe connectors. Independent voltage regulation.

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe6/8 Other Features Review Price
Antec TruePower Trio TP3 550 550w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 42A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 2/0 Single 12v rail, not triple SilentPCReview ~$119
Antec TruePower Trio TP3 650 650w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 52A Image:Cross.png Image:Cross.png Image:Tick.png Image:Cross.png 2/0 Single 12v rail, not triple jonnyGURU ~$156
Corsair HX Series CMPSU-520HX 520w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 40A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/2 Single 12v rail, not triple SPCR, jonnyGURU ~$129
Corsair VX Series VX550W 550w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 41A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 Single 12v rail, not triple jonnyGURU ~$130
Corsair HX Series CMPSU-620HX 620w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 50A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/2 Single 12v rail, not triple jonnyGURU, X-bit labs, SPCR, HardOCP ~$165
Enermax Modu82+ 625 625w Image:Tick.png Image:Tick.png Image:Tick.png 50A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/4! Extreme silence SPCR ~$170
Seasonic S12 Energy Plus SS-550HT 550w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 41A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 2/0 Very quiet, single 12V rail, not quadruple SPCR ~$150
Seasonic M12 M12-500 500W Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png 38A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 2/0 Actually single 12V rail ~$165
Thermaltake ToughPower W0103 600w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 48A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/0 X-bit labs ~$158
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Premium high end (under $300)

700w or greater, 56A or greater on 12V rail(s) combined, 4 or more PCIe connectors of those at least 2 8pin. Independent voltage regulation.

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe 6/8 Other Features Review Price
Antec Signature SG-850 850w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Cross.png 65A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 2/2 jonnyGURU, HardOCP ~$280
Coolermaster Real Power Pro RS-850-EMBA 850w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 70A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/2 X-bit labs ~$249
PC Power & Cooling Silencer 750W RED 750w Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 60A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 2/2 Hardwaresecrets, HardOCP ~$249
SilverStone Olympia OP1000 1000W Image:Tick.png Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 80A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 4/2 Older revisions had no 8pin PCIE HardOCP ~$260
Zalman ZM ZM850-HP 850w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 60A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 2/2 X-bit labs ~$220
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Insane (no price limit)

850w or greater, 65A or greater on 12V rail(s) combined, 6 or more PCIe connectors and of those at least 3 8pin PCIe. For 3 way SLI/Crossfire with extreme cooling.

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe 6/8 Other Features Review Price
Corsair HX 1000 1000w Image:Tick.pngImage:Tick.png80A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/6 HardOCP ~$330
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Quiet Power supplies

These power supplies have proven to be the some of the quietest avaliable, generally as confirmed by a SilentPCReview or equivelent review. PSU fan speed under typical load should be < 850rpm for 140/135mm/120mm fans, and < 1200rpm for 80mm fans. This is far from an exhaustive list, most corsair and seasonic brands for example could be put in this category (except the > 700w models that are louder).

Manufacturer Range Model / Link Watts 12V Rail(s) EPS Modular A/PFC Sleeved PCIe 6/8 Recommended for: Review Price
Coolermaster eXtreme Power RS-430-PCAR 430w Image:Tick.png Image:Tick.png Image:Cross.png Image:Cross.png 29A Image:Cross.png Image:Cross.png Image:Cross.png Image:Cross.png 1 Budget silencers jonnyGURU ~$46
Enermax Modu82+ 525 525w Image:Tick.png Image:Tick.png Image:Tick.png 50A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/3! Extreme silence Anandtech ~$115
Enermax Modu82+ 625 625w Image:Tick.png Image:Tick.png Image:Tick.png 50A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 0/4! Extreme silence SPCR ~$180
Coolermaster Real Power Pro RS-850-EMBA 850w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 70A Image:Tick.png Image:Cross.png Image:Tick.png Image:Tick.png 4/2 Quad SLI overclockers X-bit labs ~$249
Zalman ZM ZM850-HP 850w Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 60A Image:Tick.png Image:Tick.png Image:Tick.png Image:Tick.png 4/2 Quad SLI overclockers X-bit labs ~$220
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Top Value Case and PSU Combos

Here is a list of cases that come with decent psu's (ie good brand, 24/20+4pin and pcie connectors, decent 12V rail(s), unlike most of the $40-$80 cases that have poor quality generic psu's in them. Avoid all Thermaltake bundled case + psu combos for reasons listed in Thermaltake_PSUs, unless you only ever plan to run light or older systems, since they are deceptively lableled (rated for 250w by oem which thermaltake then sticks a '400w' or '430w' label on it), and are based on the obselete atx1.3 standard so are not designed to run modern systems.

Manufacturer Range Model / Link PSU Model Watts 12V Rail(s) PCIe Case Type Review Price
Asus TA-582 Bespec 350w Image:Tick.png Image:Tick.png 25A 1 mid tower case ~$70
Antec Solution NSK2400 SU-380W 380w Image:Tick.png Image:Tick.png 28A 1 HTPC suited desktop case SilentPCReview ~$140
Antec Solution NSK4480/b EA-380W 380w Image:Tick.png Image:Cross.png 27A 1 Small mid tower (fits full size atx board) ~$101
Antec Solution NSK6500 EA-430W 430w Image:Tick.png Image:Cross.png 32A 1 Larger midi tower ~$140
Antec Sonata Sonata 3 EA-500D 500w Image:Tick.png Image:Tick.png 34A 2 Larger midi tower ~$175
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Trusted Power Supply Makers

Here is a list of user supplied information from the forums.

Along the lines of "trusted" PSU's (considered brand name) are:

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Some Not Recommended Power Supply Makers

Some of these may not seem dodgy and some may be because of numerous "bad" reports, but these power supplies are almost definitely of questionable quality or have low specifications (and/or have far inflated wattage ratings / rail current ratings of what the power supply can actually do under normal conditions). Just because you can get away with one of these power supplies does not mean the next guy will, or the guy after that, whatever.

  • Aspire
  • Auriga - AVOID AT ALL COSTS. Might work today, or tomorrow, or the next month, BUT down the track you'll be unable to turn them on. So far had a 50% return rate on them after 3 years approx use. Expecting the other 50% to fail in time as well.
  • Clipper pro
  • Codegen - SUBJECTIVE, I've got one 400W working like 16h/day for 6 years and still running. Plus I've seen about 50 cheapies of this brand gone and hasn't come back for warranty. They're the only brand offering 5 YEARS warranty on them. Main issue is the vast majority of models are all old designs, OK for P3/athlonxp days but poor voltage stability on newer systems, which is unacceptable given ATX v2.0 has been around for years and they still haven't got any 'proper' ATX 2.0 psu's with decent 12V specs (only rebadged old designs that are deceptively labeled). example (550w psu, 18A 12V rail)
  • Coolmax
  • Generic (duh)
  • Hairong
  • Honli
  • Logisys
  • Mad Dog
  • MGE / XGbox
  • Omni - Stay away from their cheap product lines. But their mid-end one is OK though (e.g. 500W silent, 12cm fan, honey comb vent).
  • Powmax
  • RexPower
  • Ritmo
  • SHAW
  • TT (Not to be confused with ThermalTake) - These babies blow capacitors like no other!!
  • YoungYear (OEM for MGE / XGbox and Aspire)
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Important issues with popular PSU brands

  • Antec: The first few revisions (before A3) of the neo HE series had lots of incompatibility issues with various motherboards, Asus in particular. Particularly the 430w model seems to be having issues even in latest revisions, so its probably best to avoid it altogether. rev A4 and above should be fine mostly. Also the smartpower series is having high return/fault rates currently, so is not recommended. Finally both the smartpower and truepower 1.0/2.0 (3.0 is fine) series are all full of Fuhjyyu caps, so often die after as little as 6 months in a warm case. All other Antec psu's should be fine however, the newer models all have at least passable capacitors.
  • Coolermaster: their psu's are sourced of good oem's, but some dubious decisions are made in marketing their psu's. In particular the xtremepower 600w (Johnnyguru review) is based on a 500w Seventeam unit (so therefore can't do the full 600w advertisied). Apparantly Coolermaster marketing said they 'tweaked' the rails to get the extra 100W wattage and extra 6A 12V rating, but from johnyguru's review its obvious that past 500W (what the oem rated it for), the psu unusable. Their 550w 'real power' model is better though, actually does its rated wattage rating and considerably more than the rated total 12V rating Johnnyguru review
  • Enermax: Some of their older models like the liberty series used some cheap capacitors that failed . Newer infiniti/modu series etc are better with all japanese capacitors.
  • FSP: Avoid any epsilon based power supply above 500w. They are all group regulated designs with increasingly worse voltage ripple and regulation issues. The design is only really good for 600w of clean power, yet is avaliable in models as high as 1010w.
  • OCZ: Avoid the ocz modstream for anything but light to medium single videocard systems due to huge cross loading requirements for anything past about 15-20A load on 12V rail (psu starts to overvolts the 5V rail and undervolts the 12V rail). Also the OCZ gamexstream/silentxstream series above 500w suffer from ripple issues, and somewhat poor voltage regulation, as they are FSP epsilon builds.
  • SilenX: Are also Fortron rebrands (some of them any way), but are overpriced for what they are.
  • Silverstone: The older revisions 650w ZEUS and ST60F psu puts both pcie power connectors on the same 12V rail (fixed in latest revision), so will have same problems as dual rail psu's with high end SLI (workaround is to use molex-pcie adapter for 2nd videocard, then all goes well). Also the strider series