First build and I bought the wrong PSU

[WestonG]

I recently bought all the components I needed from SCAN to build my first PC. But I did not realize that the PSU I bought doesn't have enough wattage for my build. I don't want to try and use it in case my computer blows up or something, and I cannot afford a new, more powerful one now. Is there any way I can exchange or return it?

[drharvey12]

I'd phone Scan up and ask them for an RMA number to return it. You should be ok. I recently raised an RMA for 12GB of RAM for a build and then later decided I didn't need it.

As it is an "unwanted" item assuming it's the same process as I went through you need to request the RMA from them. Then you will need to send it back to them (well packaged). They will then issue a refund within 10 days of the part being booked back in.

Are you sure the wattage is too low. For most rigs a good 550 watt PSU is enough. You can always use an online calculator to determine the PSU you need. Corsair have one on their website: http://www.corsair.com/learn_n_explore/?psu=yes

It's hardly accurate to the watt but it should give you an idea

[WestonG]

I used a calculator and put all my info and components in, it told me I need 367w at high usage and 317 idle. I have:

-Phenom x4 965 3.4 black
-HD 6850
-8GB Kingston hyper x genesis (1600mhz)
-500GB 7200rpm (3gb/s) HDD
-450w 80 plus PSU (I didn't realize at the time that this is considered rather low)

So, do you think the results are about right? And If so, do you think I could run with that PSU?
Thanks for your help.

[drharvey12]

Have you got a link to the Scan webpage for the PSU you bought?

Some PSU's are rated at 450 watts but only a portion of that is available on the 12v rail which is what powers most of the components in your PC, ie Graphics cards.... I believe that the Scan site confirms how much power is available on the 12v rail for the PSU's they sell.

Are you planning on overclocking either the processor or the graphics card? Doing either will require more power from the PSU.

Generally speaking you don't want a cheap PSU. Certainly having a poor PSU can decrease system stability and one that doesn't protect your components from over & under-voltage...etc can even cause damage to your components if it goes wrong down the line. I always tend to go for brands such as Corsair & Seasonic as I've used those in the past without problems. A good quality PSU at the correct wattage for your system is also better than a cheap PSU with a much higher wattage. PSU's tend to be most efficient at 80% load so having say a 850watt PSU will mean you only ever run it at less than 50% load and it will be reasonably inefficient. However should you want to add more to your PC at a later date it does allow you to do so without having to change out the PSU as well so it is worth considering one that has slightly more wattage than you need if you think you might upgrade in the future. Good quality PSU's come with a 5 or 7 year guarantee so getting a good one should mean you don't have to keep changing them down the line.

[Edit: came across this for calculating wattage on the 12v rail which is where you want your wattage to be:
To calculate your (PSU) power supply unit's wattage you have to first get its amperage and voltage. Then, work out their product, as it is the wattage. Wattage is determined by multiplying voltage by amperage. For instance, if it is labelled +12V and 18A then the wattage is 216W.
Just checked it against the specs on my PSU and it works out perfectly ]

[Edit 2: Also just seen that in the <520w range it looks as though even Corsair PSU's come with a 2 year warranty as I guess the parts used in them are lower quality (which makes sense considering the price differential). My 1050 watt Corsair PSU I just bought comes with a 7 year warranty so the bigger ones are obviously expected to last a lot longer!].