Whilst responding to a plea for advice in recent thread, I got to wondering as to just
how many CTD’s are attributable to failing and/or just plainly under specified PSU’s.
PSU’s are too often treated as an afterthought when considering a PC system in the round.
This is flawed thinking!
A good quality, appropriately specified PSU is as important [albeit not as sexy]
and as integral to your systems performance and long term reliability as the
Mobo, CPU and GPU etc.
To be clear: an incorrectly specced PSU can transform an otherwise perfectly reliable system
into a glitch giving, possibly CTD ridden, pariah of a machine that will ultimately disappoint.
This then is a guide to all those [particularly those new to our hobby] who have never
given their PSU the due consideration it deserves.
So, you find yourself in the market for a shiny new PSU, eh? Well, don’t turn the process
into a lottery! Consider the following:
i. The source:
Has the PSU been produced by a known and respected maker? And, are you buying it from
a known and respected supplier? -There’s a lot of c**p out there. Don’t be tempted!
ii. The physical specification:
Size matters! Avoid that potential ‘home goal’ by making sure it will actually, physically
fit into your case. - modern PSU’s are universal with regard to screwing in.
iii. The Electrical specification [1]:
PSU’s are normally classed in terms of the manufacturers rated Wattage*.
Very sensible! Because this PSU Wattage is, when compared to your total system Wattage**,
the primary indicator as to which PSU is right for your system.
But know this: the PSU’s rated Wattage MUST ALWAYS EXCEED the total system Wattage.
iv. The Electrical specification [2]:
Make sure your PSU has at least two busses or rails [this is in effect as if there are
multiple PSU’s in the one case]. - As far as I know all modern GPU’s require these
‘split’ rail power lines to operate reliably.
v. Optional:
And finally, do yourself a big favour. Buy a PSU that has non-tethered [plug-in-able] cabling.
- So much better if you desire that ‘clean’ and finished look to your installation.
- The Wattage can be derived simply from: Amps x Volts = Watts.
So, for our purposes, Amps is the required power output of the PSU and Volts is the voltage of
your countries domestic mains supply.
** The total system Wattage is quite simply the sum of all the manufactures rated
Wattages for each and every individual component [CPU, GPU, RAM, Storage devices, etc]
that require power and are a part of your system.
Notes:-
Consider this hypothetical case: two identical car engines - rated for a maximum speed of say
120 mph - are set up to run indefinitely. Engine A is set up to run at a constant 30 mph,
whilst engine B will run at a constant 100 mph. Their respective speeds are then, the only difference!
And the result of all this contriving? Not only does engine B ‘experience’ far more stress
than it’s slower doppelganger but, all things being equal, engine B will also suffer a catastrophic
failure far sooner.
This analogy is directly applicable to all PSU’s when under load!
Thus, I strongly recommend you make sure your PSU is over specified.
If, for example, your TS Wattage is say 500 watts then don’t use a 550 Watt PSU!
A 650 or 750 watt PSU would be a far wiser choice.
You will, of course, have to pay a little more for all this PSU goodness.
But what price long term reliability?
I bought my own [1000 Watt] PSU 4 years ago! It was then, and remains now, healthily over specified.
It has delivered countless hours of quiet and reliable performance.
And will, I fully expect, survive my next upgrade and continue to give me peace of mind
for the foreseeable future.
There are many TS Wattage and PSU Wattage calculators to be found on-line these days.
These can be very useful. but use more than one as a crosscheck, eh.
As always I urge you all to do your own research.
Don’t just rely on anything as written here. Maybe I have missed something.
Maybe I have raised points ripe for debate.
And, as always when researching on-line, beware of the peddlers of anything oily that has been
extracted from a snake!
Addendum:
In this post I invited others to offer additions/corrections to anything deemed misleading
or erroneous. And in an effort - for ease of reading - to keep any points raised at the top
of the pile, as it were, I will try to keep abreast of any developments and incorporate them
immediately below.
Good evidence [as provided by Aeluwas] proves that point iv above is no longer applicable and can be ignored.