Most standard computers can take any standard Power Supply Unit with standard connectors. This means it is fairly easy to replace a PSU using an other model number, providing the size or the screw holes match.

Note that our replacement Power Supply Units are not direct replacements. The brand, model number, electric specifications and connectors may vary slightly from your original PSU and we cannot guarantee that they are 100% compatible with your hardware specifications. They are only high quality alternative PSUs and they do the job with no problem in most cases.
In rare cases you may encounter some issues and some slight adjustment may be required to fit your computer (additional connector adaptors, etc...).
Should you have any query, please do not hesitate to send us pictures of your PSU, PSU label, connectors, rear of chassis, inside of PC, together with your original PSU and PC model numbers. We usually provide a simple solution for most issues described bellowEmail us here.
Should you still need to return your item please request an RMA Number and use this Return form.
Please see a list of the questions you might have about a PSU purchased from us. 

The PSU connectors are wrong, too short or missing
The PSU wattage is wrong
The PSU voltage is wrong
The PSU fan position is wrong
The PSU current ratings are wrong
The PSU is missing the monitor outlet
The PSU model number is correct but the specifications are wrong
The PSU size is wrong
The PSU does not fit
10 The PSU does not work at all or works intermittently


1 The PSU connectors are wrong, too short or missing.
Main ATX connector:
-Older boards require a 20pin ATX connector and new boards require a 24pin connector, so most PSUs have a 20+4pin to fit all boards. Check if the new PSU has this additional 4pin square connector (with yellow, orange, red and black wires) often labelled “24”. It needs to be attached to the side of the 20pin connector and there is only one way to plug it in. Not to be mistaken for the square 4pin P4 connector with yellow and black wires. This similar looking connector has a different shape and will not fit near the 20pin connector anyway.
Some PSUs have a 24pin or a 20pin connector only and may require an adaptor (20 to 24pin or 24 to 20pin). Please ask for a suitable adaptor if required.
Note that It is OK to plug a 24pin PSU connector into a 20pin Motherboard socket, leaving the extra 4pin hanging on the side (providing there is no components obstructing the insertion on the connector).
20+4Pin ATX connector    PSU ATX connector 
When a 20pin connector is paired with an extra 4pin connector, its clip is wide and off centre.
When a 20pin connector is NOT paired with an extra 4pin connector, its clip is small and in the middle.
24pin connector in 20pin socket     24pin connector in 20pin socket
24pin connector plugged into a 20pin motherboard socket.
In the second picture, components are in the way, so a 20 to 24pin adaptor is required. 
-Some odd PSUs have a special main connector (NAS boxes...). It may physically fit the motherboard but if the wire colours are different, damage may result. Please check your connector pinout and ask for availability.
24pin ATX connector pinout
Standard ATX 24pin connector pinout
8pin Connector:
There are 2 types of similar looking 8pin connectors on a PSU. Their pinout is slightly different:
-8pin EPS 12Volt connector for the motherboard. Usually on high end PSU. Also available as optional adaptors (4pin-to-8pin EPS or Molex-to-8pin EPS adaptors).
-8pin (or 6+2pin) PCI-Express connector, connected to the motherboard or to the PCI-E cards. Usually on high end PSU. Also available as optional adaptors (6pin-to-8pin PCI-E or Molex-to-8pin PCI-E adaptors). Note that a beveled second pin goes to the PCI-E cards and a square pin goes to the motherboard.

AT P8 & P9 Connectors (on older type of PSUs)
-The old type of AT PSU for legacy AT systems has been discontinued. Our replacement AT PSU comes with P8 & P9 connectors with standard colour wires. However, some AT PSU (such as the famous SFI-300G) may have wires with different colours. This is fine since their currents are the same. Therefore, our AT PSUs can safely replace your AT PSU even if some wire colours are different.

SPI-300G AT PSU Wire colours                                               Standard AT PSU wire colours

Other connectors:
-All our PSUs come with standard connectors, however, the types and numbers of connectors may vary slightly depending on PSU model numbers and versions. If you requires additional connectors, we can supply a wide range of adaptors or extensions to meet your needs.

Available adaptors / extensions:


20pin extension

24pin extension

20Pin to mini 24pin adaptor

20pin (PSU) to 24pin (Board) adaptor

24pin (PSU) to 20pin (Board) adaptor

1Molex to 2Molex adaptor

1Molex to 1SATA adaptor

1Molex to 1Angled SATA adaptor

1Molex to 2SATA adaptor

1Molex to 4pin P4 adaptor

4pin P4 extension

1Molex to Floppy adaptor

1Molex to 3pin Fan adaptor

2Molex to 6pin PCI-E adaptor

2Molex to 6+2pin PCI-E adaptor

4pin P4 to 8pin EPS adaptor

PSU adaptor

-Some SATA connectors in slim chassis may be to long to fit due to a lack of room behind the drives. Ask for a "Right Angled SATA Adaptor".

Right angles SATA connector    Standard SATA connector
Right Angled SATA connector                                   Standard SATA connector
-Should you a require a non standard connector, it may possible to cut it off your old PSU and DIY reconnect it (at your own risk) to the new PSU. In order to keep the new PSU intact and its warranty valid, we recommend to work on a cable extension rather than cutting the PSU cables. Contact us to see if we can help.
2 The PSU Wattage (power output) is wrong.
-Most of our power supplies deliver 250 to 350watt which is usually sufficient for a standard home or office PC. A hungry PC such as a gaming machine or industrial server may require a higher 400 to 500W PSU. A wattage higher than your original is fine and will not damage your PC. The PC only draws the amount of power it requires. In fact, the more power the better. It allows a more stable system and more future upgrade possibilities. The wattage is indicated in the PSU model number and on the label.
300Watt output PSU                                                                              300W output PSU (276+24)        
3 The PSU Voltage is wrong.
-Some PSUs are Auto Range (Full Range) and switch automatically between 110 and 230volts. Some PSUs have a small red volt switch that needs to be set manually to your country's voltage before connecting the PSU to the Mains. Some of our PSU are only set to 230Volts and are therefore not suitable for 110volt countries. Please check the "AC Input" information on the PSU label and check if there is a red switch near the power socket.
Suitable for 110 & 230V countries (No volt switch. The PSU is Auto Range. The voltage is changed automatic)
    Volt switch
Suitable for 230V countries only (No red volt switch, The PSU is set to 230V only)
    Red Volt switch 
Suitable for 110 & 230V countries (With red volt switch. The voltage is changed manually)
4 The PSU fan position is wrong.
-The position of the fan does not usually affect the efficiency of the cooling. The hot air is sucked out from the inside of the chassis and PSU, to the outside. In some rare cases a PSU with a fan situated at the top may not fit a small or 2U chassis due to the lack of room for ventilation. Most new PSUs have a quieter and more efficient 120mm fan on top. The fan usually faces the board / CPU once the PSU is installed. Ask for a PSU with an 80mm fan at the front if required.
PSU fans
PSUs with different fan configurations. The air flow remains the same. A 120mm fan tends to be more efficient and more quiet.
The 1U PSU on left has the fan at the rear (near the cables) and the 1U PSU on the right has the fan at the front (near the power socket).
The air flow remains the same. The arrows marked on the fans show the air flow and rotation direction.
The air usually comes out from the side where the label is.
5 The PSU current ratings are wrong.
-All PSUs have slightly different current rating shown on the PSU label. This is usually not a problem, unless you have a very specific rating requirements for a special motherboard.
-Latest PSUs do not have the obsolete -5Volt white wire in pin 20 (left empty). Should you require this -5V rail, used for older boards with ISA slots, order a suitable PSU.
Missing -5V rail wite wire
Older PSU with -5Volt Rail (white wire in pin 20)                  New PSU with no white wire               
6 The PSU is missing the monitor outlet.
-Some older PSUs, especially AT PSUs, used to have a Monitor Outlet next to the Mains Power Inlet. This was for the monitor or other devices. Latest PSUs do not have this Power Outlet. The monitor outlet provides the same voltage as the one from the mains, so you can get round this by using a standard PC power cord to power the monitor. A twin power cord can also be used to minimise cabling. If you really need a monitor outlet, order one of our rare PSU with a monitor outlet.

Monitor outlet on older type of PSUs.
Monitor outlet
The monitor or other devices can be plugged directly to Mains.

7 The PSU model number is correct but the specifications are wrong.
-In rare cases two PSUs with identical model number and size have different specifications or connectors. This is because a standard PSU was modified by the manufacturer to fit a non standard PC and the model number was not changed. This can lead to confusion when ordering a replacement for a non standard PSU, so please check your requirement or contact us for assistance as we cannot be held responsible for errors resulting from such confusion.
-If available, we can provide parts to go with our PSUs in order to match your requirements, however we cannot refund the cost of parts purchased from other suppliers (Connectors, Adaptors, Extension cables...).

These two PSUs have the same model number FSP350-701UJ and look identical however their connectors are different. The non standard PSU on the left has 2 special connectors for QNAP NAS boxes and the standard PSU on the right has all the usual ATX connectors (Molex, SATA, Floppy, 20pin etc...).
8 The PSU size is wrong.
-Our PSU sometimes have a different size or shape from the original but most of the screw holes should match your chassis. Some PSUs may be supplied with a metal adaptor bracket in order to fit your chassis, but this would be clearly indicated on the product page.
HP Pavilion replacement PSU
Our PSU on the left replaces the two discontinued PSU on the right. The screw holes are the same.
PSU with adaptor
Our PSU on the left replaces the discontinued PSU on the right. A metal adaptor bracket is supplied in order to match the screw holes.
9 The PSU does not fit.
-Most screw holes on our PSUs match the chassis and are sufficient to hold it in place, however, some screw holes may be missing or our fitting bracket may not fit perfectly.
-Sometimes, the shape of the PSU cut out (PSU hole) on the chassis does not allow the installation of a PSU due to the position of the cooling fan, the On/Off switch or the power inlet. Please check compatibility, ask for the switch to be removed or ask for an alternative PSU. Check this guide.
PSU switch does not fit
On the right, this is an example of a PSU which had the On/Off switch removed in order to fit a particular PC with no holes for the switch.
These two computers can only take a specific type of PSU due to the shape of the cut out on the chassis.
-Some PSUs have an indent and hold on a hook in the chassis. If our replacement PSU does not have the indent, it may be necessary to flatten the hook in order to allow the PSU to sit flat.
PSU indent    PSU indent
PSU with indent                                                                                   PSU with NO indent
10 The PSU does not work at all or works intermittently.
-Our high quality PSUs are very reliable and are tested prior dispatch so they are unlikely to arrive faulty, unless they have sustained some damage during transit. We suggest you to retest the PSU by making a bridge with a paper clip between the Green and any Black wire before connecting the PSU to the mains.
See bellow how or check this guide.
If the fan does not spin, the PSU may be dead, please open a return case and we will replace or refund it.
If the fan spins, the PSU is likely to be working and there may be an other issue with your PC (faulty motherboard etc...), please open a return case and we will refund it.
-Some PSUs may appear to work intermittently. This is usually not due to a lack of power (please compare the wattage with your original PSU's). It is often due to an unexplained electrical incompatibility issue. This issue as been reported with some HP Pavilion computers for which a more performant PSU has solved the problem.
How to test an ATX PSU
This is how to test an ATX PSU
Disclaimer of Liability:
-The information contained in our Power Supply compatibility lists is accurate and reliable to the best of our knowledge, however, we do not assume any liability whatsoever for the accuracy and completeness of the list.
-We cannot be held responsible for any incompatibility or safety issue, damage, injury or loss of any kind related to the use of our products.
-It is the responsibility of the buyer to install and use our items in a safe and suitable manner and we cannot be held responsible for any misuse of our products.
-Anyone who is not competent to carry out the installation of our products should seek professional assistance.