Is 750W overkill for a 350-450W build?

[vulgarfate]

I see this asked a lot but obviously times change and components upgrade so it's nicer to see more recent thoughts, I suppose

My build will be this: http://uk.pcpartpicker.com/user/Ridgey/saved/yspNnQ (just got to get the R7 260X which is replacing a current GTX 460, other than that everything is the same)

Calculators tell me the wattage it will use/need is in between 300-400, and iirc one said 450 at max. As a birthday gift (therefore I didn't waste my money) my father bought me an EVGA 750W G2 PSU as my "PC building advisor" thought I should've gotten with my current build, and even if it is overkill, I can hang onto it if I decide to upgrade to something that needs 750W.

Then again lots of people are telling me 500W is fine. I'm hoping that if it's safe to upgrade to a 750W so I can sell my 500W on, but if it isn't safe and is at risk of being too underpowered, I won't upgrade.

 

[helpstar]

It will run totally safe. Don't worry. Only thing is, that it won't run at its best efficiency.

 

[vulgarfate]

It will run totally safe. Don't worry. Only thing is, that it won't run at its best efficiency.

Thank you! Just a bit worried since I know PSU's can be underpowered and it can be dangerous, definitely after skimming through the booklet and it saying "Underpowered Protection" or something.

 

[guanyu210379]

Not only efficiency issue, PSUs with higher power rating should be usually more expensive.
Other that efficiency and price, there is nothing to worry about.

 

[vulgarfate]

Not only efficiency issue, PSUs with higher power rating should be usually more expensive.
Other that efficiency and price, there is nothing to worry about.

Like I said, not bought it so no money wasted there, plus I think I can hang onto it for at least a few years since PSU's don't change too often, unlike how GPU's and CPU's are coming out all the time, but I could be wrong.

With the efficiency issue, what problems could I run into?

 

[guanyu210379]

PSUs are specified to for example 80% efficiency.
Let make it as simple as possible.
You are drawing e.g. 100W from the plug but will provide only 80W to the PC.
The 80% is however bound to certain load percentage. e.g. 70% load.
If you are using only about 40% load, it is possible that the PSU is working only with e.g. 70% efficiency.
This means, the PSU is drawing 100W to supply 70W.
There is no big deal with efficiency issue.

 

[vulgarfate]

PSUs are specified to for example 80% efficiency.
Let make it as simple as possible.
You are drawing e.g. 100W from the plug but will provide only 80W to the PC.
The 80% is however bound to certain load percentage. e.g. 70% load.
If you are using only about 40% load, it is possible that the PSU is working only with e.g. 70% efficiency.
This means, the PSU is drawing 100W to supply 70W.
There is no big deal with efficiency issue.

Ah, thanks! Makes sense Will that kill off the PSU a bit quicker than it would if it was at 100%/more than 70% efficiency?

 

[guanyu210379]

Efficiency does not kill PSUs, max efficiency is also around certain load e.g. 70-80% load, if you go beyond that e.g. near 100%, the PSU is usually already moving again away from the peak specified efficiency.

PSUs will deteriorate faster if you run it near 100% capacity for longer time.
Good PSUs can even survive a bit higher than 100% capacity/load but only for a short time.
Good PSU manufacturers build even some extra unwritten PSU capacity but you should not test this.
This is why, if you are going to build a 24/7 PC, you will need bigger PSUs than those, who want to run the PC 8 hours per day even if the PC's spec are the 100% same.