Help choosing PSU...

MrDavies

MrDavies

MrDavies

Associate
Joined
5 Jun 2017
Posts
132
Hi guys,

I'm relatively new to this PC building scene and still don't trust myself choosing a correct PSU. I'm guessing it's not as complicated as it seems but I'd feel better seeking advice.

Currently in the process of putting together the following system from spare parts and black friday purchases as a Christmas gift for my brother;

My basket at Overclockers UK:
Total: £893.05 (includes shipping: £11.10)​
​

The case has a shroud for the PSU so it doesn't need to look the part but modular is preferable. I know he has an old Corsair 750W at the moment but I thought that could be drastic overkill and not very efficient.

Thanks in advance.
 
I tend to workout roughly how much power I need and then pretty much double it to allow for future upgrades and make sure the PSU has no problems delivering stable power over a long period.

The above suggestion may be fine as it is a good branded PSU but I would probably go for 700w or more unless you are restricted by budget so you never have to think about it again.
 
DarkHorizon472 said:
I tend to workout roughly how much power I need and then pretty much double it to allow for future upgrades and make sure the PSU has no problems delivering stable power over a long period.

The above suggestion may be fine as it is a good branded PSU but I would probably go for 700w or more unless you are restricted by budget so you never have to think about it again.
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He doesn't need anywhere 700W for that system. Unless he plans on getting a GTX 1080 ti then 550W is more than enough.
 
I would second that 550w is definitely enough for that system plus a future upgrade (unless that upgrade is a TI series GPU). 650w would give you peace of mind I guess and the same seasonic at 650w is just £10 more.
 
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As a slightly alternative build:

If you saved some money on the GPU, fans and the PSU (450w is fine for that PC) you could get a Ryzen 1700 instead of 1600:

My basket at Overclockers UK:
Total: £981.00 (includes shipping: £11.10)
​

This Bitfenix unit is slightly worse then the Seasonic, but is by no means a bad unit.



But, the Seasonic would definitely offer a bit more future upgrade headroom, is fully modular and comes with double the warranty.
 
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DarkHorizon472 said:
I tend to workout roughly how much power I need and then pretty much double it.
Click to expand...

After I graduated my first job was at a software company where one of the owners was a software developer on Concorde, he had programmed the fly by wire, and also head up display, he also worked on defence missiles etc during his career, also electronics hardware etc.

This was his advice on PSU's. He said you never skimp on the PSU, you buy known quality units, work out your total computer wattage and buy a PSU that's double the highest load. Obviously with very high wattage GPU's doubling the peak load is not always feasible, however where possible everyone should install PSU's that are double the systems peak total wattage.
 
JasonM said:
After I graduated my first job was at a software company where one of the owners was a software developer on Concorde, he had programmed the fly by wire, and also head up display, he also worked on defence missiles etc during his career, also electronics hardware etc.

This was his advice on PSU's. He said you never skimp on the PSU, you buy known quality units, work out your total computer wattage and buy a PSU that's double the highest load. Obviously with very high wattage GPU's doubling the peak load is not always feasible, however where possible everyone should install PSU's that are double the systems peak total wattage.
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That’s my thinking.
 
JasonM said:
After I graduated my first job was at a software company where one of the owners was a software developer on Concorde, he had programmed the fly by wire, and also head up display, he also worked on defence missiles etc during his career, also electronics hardware etc.

This was his advice on PSU's. He said you never skimp on the PSU, you buy known quality units, work out your total computer wattage and buy a PSU that's double the highest load. Obviously with very high wattage GPU's doubling the peak load is not always feasible, however where possible everyone should install PSU's that are double the systems peak total wattage.
Click to expand...

He is right about not skimping on quality but there is no need to buy a unit that is twice what you need. The difference in efficiency is very small so you are not going to save any money. So a 550W Gold unit for example that is running at 80% load will be hitting about 90% efficiency. The same unit running at optimal load i.e 50% will be hitting about 92% efficiency.

You can see this in the chart below for the EVGA G2 550W.

http://www.tomshardware.co.uk/evga-supernova-550-g2-power-supply,review-33302-5.html
 
lee32uk said:
He is right about not skimping on quality but there is no need to buy a unit that is twice what you need. The difference in efficiency is very small so you are not going to save any money. So a 550W Gold unit for example that is running at 80% load will be hitting about 90% efficiency. The same unit running at optimal load i.e 50% will be hitting about 92% efficiency.

You can see this in the chart below for the EVGA G2 550W.

http://www.tomshardware.co.uk/evga-supernova-550-g2-power-supply,review-33302-5.html
Click to expand...

I agree about the efficiency but doubling up the total peak wattage is more about redundancy, PSU capacitors also degrade slightly over the years so your compensating for this also.
 
JasonM said:
I agree about the efficiency but doubling up the total peak wattage is more about redundancy, PSU capacitors also degrade slightly over the years so your compensating for this also.
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A good quality unit such as the Seasonic Focus should easily last the length of it's warranty. They are not going to give you a 10 year warranty if they didn't have faith in their product. The Prime series has 12 years. Yes degradation is a thing but it isn't something you need to worry about unless you buy a cheap Chinese firecracker.
 
lee32uk said:
A good quality unit such as the Seasonic Focus should easily last the length of it's warranty. They are not going to give you a 10 year warranty if they didn't have faith in their product. The Prime series has 12 years. Yes degradation is a thing but it isn't something you need to worry about unless you buy a cheap Chinese firecracker.
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I think the Seasonics are probably the best PSU's on the market, always good but moved the game on in 2009 with X series. Still think its good practice to over spec the PSU. If a system has a peak power of 300w nothing wrong with a 500-600w Seasonic, worth the extra redundancy for less load on PSU fan, and the reserve should cope with power spikes better.
 
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