How Not To Build A PC (Part 1) - Underspecified PSU & Wrongly mounted cooler

5/18/2012 5:30:25 PM

Building a PC is not rocket science, but there are still many potential pitfalls. Ian Jackson looks at ten common mishaps you should aim to avoid!

Motherboard shorting on the case

Description: A computer motherboard can be turned on by shorting the power switch pins

A computer motherboard can be turned on by shorting the power switch pins

An inevitable part of any PC build is mounting your shiny new motherboard into the case. Most cases hold the board in place via brass standoffs that you screw into the motherboard tray. Since there are several different form factors of motherboard, there are usually far more mounting holes than you will actually need. A common mistake made by first time PC builders is to screw in all of the brass standoffs, regardless of whether they marry up with a hole on motherboard. The trouble with doing this is that you have a piece of sharp, conductive metal coming into contact with the board where it shouldn’t. This can damage the delicate traces on the underside of your board, or at the very least will stop it from posting due to a short. To avoid this scenario, simply check which holes in the motherboard tray marry up with those on your motherboard before screwing them in.

Underspecified PSU

Description: PSU

A lot of really cheap PC cases come bundled with PSUs that have a surprisingly high rating. These appear to be bargain – after all, why spend upwards of $60 on a branded 500W power supply when you can buy a $30 case and get one of the same capacity thrown in? This is a classic case of there being no such thing as a free lunch. These bundled power supplies are invariably quoting, at best, their peak operational voltage, or more often than not, are simply lying about the wattage they are capable of delivering. A cheap bundled PSU will probably power an entry-level system with integrated visuals capably enough, but if you have system with a powerful quad-core processor and a discrete video card, it’s not going to cut the mustard. Very few of these power supplies are actually capable of delivering any more than about 200W sustained and do so in a horribly inefficient manner. We mentioned in our buyer’s guide the value of having an 80 Plus certified PSU. Some of the cheap PSUs bundled with cases fail to achieve even 50% efficiency! This means that if your system has a requirement of 100W to tick over, the PSU will be pulling 200W from the wall and wasting this energy in the AC-to-DC conversion process.

An overstressed PSU can be a rather alarming thing. If your power supply makes a twittering noise or starts to smell bad when the system is at load, this normally means the capacitors, transformers and voltage regulator modules within the PSU are running beyond their specified maximum. At this point your PSU is on borrowed time. High-quality PSUs have protective circuits that cut off power to the system should operational limits be exceeded, and they have surge protection built in so that if the worst happens and the PSU blows, you don’t lose any of your hardware. Unfortunately, with cheap bundled PSUs there are no such guarantees; if a component within your cheap PSU blows, there’s a very good chance your precious motherboard, video card and hard drives could get cooked along with it.

Should a PSU within your system blow, immediately unplug it from the mains. Leave the system where it is it for a few minutes to cool down, and then while making sure you are well grounded, remove the PSU and send it back for warranty exchange. Never try to open up a PSU and DIY repairs, as this can be dangerous. PSUs are inherently non-user serviceable and their capacitors can hold a sizable amount of power even when disconnected from the mains – certainly enough to give you a nasty jolt.

Wrongly mounted cooler


Description: cooler


Modern CPU coolers are certainly a lot more forgiving than they were a decade ago, but it’s still possible to mount them incorrectly, especially if you have a complicated third-party heatsink with support for multiple socket types. This is often a mistake made by experienced system builders as well as novices, as over confidence might make you think you’re too goo to be bothered with reading instruction manuals. When tasked with a cooler you are not familiar with, always read the installation instructions, as some of the brackets and mounting arms need to be installed in quite a counter-intuitive manner. Mount the arms at the wrong point of the cooler’s base, for example, and your cooler could easily be hovering a few millimetres above the surface of the chip rather than making proper contact.

Modern processors have built-in thermal cut-offs that prevent an incorrectly mounted cooler from permanently damaging the computer. This wasn’t always the case, however – I myself have fried a number of first-generation AMD Athlon chips by thinking the cooler was properly attached when it wasn’t. if you’re repairing an older computer, you should therefore take particular notice of this common mistake!

  •  Choosing The Right Parts For Your Build (Part 6) - Picking the right RAM, Picking the right cooling, SLI and CrossFire
  •  Choosing The Right Parts For Your Build (Part 5) - Choosing your case & Picking the right storage
  •  Choosing The Right Parts For Your Build (Part 4) - Picking the right PSU
  •  Choosing The Right Parts For Your Build (Part 3) - Picking the right video card
  •  Choosing The Right Parts For Your Build (Part 2) - Choosing the right motherboard
  •  Choosing The Right Parts For Your Build (Part 1) - Picking the perfect processor
  •  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
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