Choosing The Right Parts For Your Build (Part 4) - Picking the right PSU

5/18/2012 5:23:24 PM

Picking the right PSU

Because the PSU does not contribute directly to the performance on your system, all too many users decide to purchase the cheapest supply they can get away with. This is not a sensible policy, as an inadequate supply is far more likely to fail and will contribute significantly to your system’s noise and power consumption. A common misconception is that a more powerful PSU will use more energy. This is not the case; if your system uses 300W it will only pull the power it actually requires whether you use a 300W PSU or a 1,000W model.

Description: the PSU

Many cheaper power supplies do not provide the levels of wattage they claim to. For this reason you should be very wary of buying a power supply that is priced at a level too good to be true. It’s easy to buy ‘850W’ PSUs from online retailers that cost less than $30, but these supplies will certainly not be capable of delivering this kind of power output. Modern PCs require that most of the power is capable of being delivered over the 12V rail, the most powerful of the three voltages delivered by PC power supplies. All too many manufacturers bump up their ratings by claiming the majority of the power their supplies deliver is over the 3.3V or 5V rails. In actually, the PSU’s ratings are simply fabricated.

An easy way to ensure that you get a PSU with a realistic rating is to ensure you only buy models that are 80 Plus certified. This means that you will be buying a product that has been independently tested to ensure that it firstly is capable of its quoted output, and secondly is at least 80% efficient, which will reduce your electricity bills and heat output compared to cheaper entry-level units.

If you’re using a system that only uses integrated video, then you do not need a hugely powerful PSU. Aim instead for a modestly specified unit from a high-quality manufacturer like Corsair, Enermax or OCZ. Each of these manufacturers offers good quality 400-500W PSUs with 80 Plus certification that often cost less than PSUs without certification citing unrealistic wattages.

Description: 80 Plus PSU

80 Plus PSU

If your system has a mid-ranged video card, then you should aim to feed it a little more juice. Something in the 500-600W range should be ideal, and once again you should stick to a reliable manufacturer. Again, Corsair and Enermax have suitable models, but Thermaltake also offers some competitively priced 80 Plus certified models that are worthy of consideration.

High-end single GPU systems, or those with hefty overclocks will need a 650-750W PSU. This is a popular wattage range and there is a wide selection of products available. As usual you should always look for the 80 Plus certification logo on your prospective purchase, and don’t just take the manufacturer’s word for it that they have a certificate; you can look them all up on the If you can’t find the PSU you want to buy, it probably isn’t actually 80 Plus certified after all.

The only systems needing more than 750W are those equipped with monstrously powerful dual GPU video cards or an unusual number of drives. For these systems, premium 800-850W PSUs are available. A good 850W PSU will cost you in excess of $150, with some 80 Plus Gold (>90%) certified models from Enermax and Antec costing over $225 each!

There are, of course, even higher-rated models on the market, some of which are capable of outputting 1,000-1,200W of power. These are needed for so-called ‘dream PCs’ that combine three video cards in SLI or CrossFire, or two dual-GPU cards for quad GPU support. If you have the cash to splash over $1,500 on video cards alone, you probably won’t balk at the $300-plus price of these immensely capable PSUs.

  •  Case Modding: simple case modding techniques
  •  Bundle Up To Save Some Cash!
  •  Samsung Series 5 13.3-inch Ultrabook - The Meatier Choice
  •  SteelSeries Kinzu V2 - Reacquainting With The Kinzu
  •  Lenovo ThinkCentre Edge 91z - Centre Of Thought
  •  Fuji Xerox DocuPrint M205FW - It's All Black And White
  •  ASUS Radeon HD7870 DirectCUII Top - Power For Price
  •  ASUS Essentio CM6850 Desktop PC - Essentio-ly Essential
  •  New products - First looks, May 2012 (Part 3) - MSI Z77-GD55 Motherboard, Motorola Atrix 2, NVIDIA GTX 680
  •  New products - First looks, May 2012 (Part 2) - Sony Xperia Sola, ASUS ROG Tytan CG8565, WD Thunderbolt My Duo dual-drive storage system
  •  New products - First looks, May 2012 (Part 1) - Samsung Galaxy Tab 2, Panasonic Lumix DMC-FZ47, Hewlett-Packard Z1
  •  MSI Wind U180 - The Cedar Wind
  •  ASUS U32U - For The Budget Conscious
  •  Western Digital My Book Live Duo - Full, Double Lives
  •  HP LaserJet Pro CM1415fnw - Print from The Clouds
  •  Corsair Vengeance K90 Gaming Keyboard - Aluminium and Cherry Keys
  •  Armageddon Alien II G7 - For The Ones New To The Game
  •  Toshiba Portege Z830 - Slim Cut
  •  Samsung Series 7 CHRONOS - Time, Space And Power
  •  Kingston SSDNow V+ 200 - SSDs for The Budget Conscious
    Top 10
    No Windows 7 Setup DVD Supplied With Your PC? No Problem!
    Windows 8 : End Game? (Part 4)
    Windows 8: End Game? (Part 3)
    Windows 8: End Game? (Part 2)
    Windows 8: End Game? (Part 1)
    Motorola Xoom 2 - General Tablet Use
    Nexus 7 Vs Kindle Fire
    Quad Gods - The Mobile Chip Race Is Beginning
    Linn Kiko – All-In-One Streaming System
    Install Windows Vista Home Premium SP2 Fail, What Should We Do?
    Most View
    SQL Server 2008 : Managing Security - Auditing
    Recovering from a Disaster in an Exchange Server 2010 Environment : Recovering from Database Corruption
    SQL Server 2008 : Monitoring Your Server - Monitoring Your CPU
    SQL Server 2005 : Beyond OWC: Full-On OLAP Development (part 1) - Management Studio as an MDX Client
    Samsung 900X4C - Small, Sleek And Stylish
    Zotac Zbox Id80 Plus
    Microsoft SQL Server 2008 R2 : Hierarchyid Data Type (part 1) - Creating a Hierarchy, Populating the Hierarchy, Querying the Hierarchy
    SQL Server 2008 : Transact-SQL Programming - Common Table Expressions
    Defensive Database Programming with SQL Server: The Ticket-Tracking System (part 2) - Removing the performance hit of ON UPDATE CASCADE
    Programming with DirectX : Game Input - Win32 Input
    Sharepoint 2007: Upload a File Using Web Folders
    jQuery 1.3 : Table Manipulation - Sorting and paging (part 2) : Server-side pagination & JavaScript pagination
    Mobile Application Security : The Apple iPhone - Permissions and User Controls
    Active Directory Domain Services 2008 : Create a WMI Filter, Import a WMI Filter, Export a WMI Filter
    Animations in Silverlight
    Computing Yourself Fit (Part 1)
    Parallel Programming with Microsoft .Net : Pipelines - An Example
    Windows Tips & Tricks (Part 5)
    Windows Server 2008 : Domain Name System and IPv6 - DNS in Windows Server 2008 R2
    Algorithms for Compiler Design: PEEPHOLE OPTIMIZATION