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   >  What to Upgrade
   >  Before you Begin
   >  Upgrading PC RAM
   >  Upgrading PCI/Graphics Cards
   >  Upgrading Drives
   >  Upgrading a PSU
   >  Upgrading a CPU
   >  Upgrading a Motherboard

 

Upgrading a PC Power Supply Unit (PSU)

When to Upgrade your PSU

There are only three reasons for upgrading a PC Power Supply Unit (PSU):

  • Failure of an existing unit
  • Increase Efficiency: you can now buy PSUs that are more efficient and use less power
  • Increase in Capacity: for example, you need to add new cards or drives and the current PSU does not have enough capacity to supply them

Choosing a PSU

Like Graphics Cards, there is a huge difference in price between the cheapest and the most expensive power supply unit. The most expensive will generally supply more power, run cooler and be more efficient. However, a mid-scale unit is normally a good compromise between price and performance.

The most expensive [PSUs] will generally supply more power, run cooler and be more efficient. However, a mid-scale unit is normally a good compromise between price and performance

Most PSUs have a number of standard outputs and connections, but always check that your chosen PSU has the right number and type of each connector to power everything in your PC. You also need to add up the wattage of all your PC components and make sure this is less than the PSU rating (-e.g. 300w, 500w, etc) - but always factor in some spare power for future expansion.


Removing an Existing PSU

The removal of a PSU is fairly straightforward:

  1. Before starting work, deploy anti-static controls and ensure the power is off

  2. Remove the access panel(s) from the computer case: these are located on either side of the case and will either be secured with screws or thumbwheels

  3. Remove the power connectors from the motherboard. There is normally one 24-pin plug -or one 20 pin plug and one separate 4 pin plug

  4. Remove the power connectors from all the drives

  5. Remove the power connectors from any PCI cards that have power cables plugged into them

  6. At the back of case, remove the (-normally four) screws securing the PSU unit to the rear of the chassis. In the photo below, one of the four screws has been removed:The PC rear panel showing 3 securing screws for the PSU

  7. Once the PSU has been unsecured, slide it forwards, then down and out of the case, pulling all the connectors with it

  8. Refit the access panel(s) to the computer case


Installing a new PSU

Installing a new PSU is just the reverse of the removal process:

  1. Before starting work, deploy anti-static controls and ensure the power is off

  2. Remove the access panel(s) from the computer case: these are located on either side of the case and will either be secured with screws or thumbwheels

  3. Place the PSU inside the case. If the case top cannot be removed, then place the PSU into the main compartment and lift it up to the top:

    Placing the PSU in the Case

    Once in the correct vertical position, slide the PSU unit backwards up to the backplate:Sliding the PSU to the rear of the Case

  4. At the rear of case, insert the (-normally four) screws securing the PSU unit to the rear of the chassis and tighten them: the PSU should be held securely

    Securing the PSU in the Case
  5. Pull the wiring loom through into the main compartment of the case:

    Routing the wiring loom
  6. Connect the motherboard connectors. There is normally one 24-pin plug -or one 20 pin plug and one separate 4 pin plug

  7. Connect the power connectors to all the drives

  8. Connect the power connectors to any PCI cards that have power cables plugged into them

  9. Refit the access panel(s) to the computer case


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