Power supply question

[sotosev]

As I see in people signatures, many have power supplies 700, 800watt. This happens to people who have just one VGA card and normal system parts. I wonder if there is any particular reason why you have much more power than needed to your systems?

[sobek]

Efficiency of PSUs is typically highest at 50% of maximum power yield.

[EtherealN]

They are also susceptible to degradation over time, so if the unit is intended to be in use for many years, having additional margins is a good idea.

[Daze]

Also the price difference between a 650w and an 850w is often very little. Meaning it's a no brainer going for that extra bit of power as you would have enough headroom to sli/cf in the future.

[Eddie]

In addition to all the above, if you want a modular PSU, or other high end features such as a very low noise model or a larger number of connectors they are quite often 850W and above anyway.

[Rhinox]

It is not enough to look at power output. You have to check power distribution too! In common PC you need 12V, 5V and 3.3V. But atx power supply has certain limits concerning power-shifting, i.e. you might have 700W supply, but if it gives max 150W in 3V+5V and you need more, it is not sufficient for you even total power you need is less than 700W...

 

One more thing: power supplies with higher output have generally better cooling (bigger heat-sinks, better fans, etc) because they are designed with higher level of maximum dissipated power in mind. If you need 400W from 800W-rated PSU, its fan is barely rotating and audible, while 500W-rated PSU (of the same series/efficiency/design/etc) is nearly on its max not only concerning power-output but cooling too. And while producing about the same amount of heat, it needs higher fan speed due to smaller heat sink surface...

 

PSU is the thing where user should never try cutting costs of his pc down. Unfortunatelly, exactly this is happening quite frequently...

[sotosev]

Thank you all for the info!:)

[EtherealN]

PSU is the thing where user should never try cutting costs of his pc down. Unfortunatelly, exactly this is happening quite frequently...

 

And, even more unfortunately, it's a component that almost all "off-the-shelf" manufacturers (like Dell, HP, etcetera) cut costs on, which usually ends up both limiting the lifespan of the machine, increasing the risks of catastrophic failures (I've seen a faulty PSU take the whole computer with it) as well as almost guaranteeing that a video card upgrade will also require a PSU upgrade.

[celticcoho]

And, even more unfortunately, it's a component that almost all "off-the-shelf" manufacturers (like Dell, HP, etcetera) cut costs on, which usually ends up both limiting the lifespan of the machine, increasing the risks of catastrophic failures (I've seen a faulty PSU take the whole computer with it) as well as almost guaranteeing that a video card upgrade will also require a PSU upgrade.

 

I so Agree. I run Corsair 1000w PSu's in both my machines, Having the newer GPU's require an 8pin and 6pin connector for each GPU, The 1000w has them, so upgrading in the future is no worries.:thumbup:

[sungsam]

.... or use 2 PSUs on 1 PC :music_whistling:

[Kuky]

all good reaplies... in general PSU have best efficiency at about 50-75% load so really if you estimate to be needing 400W total power for the system you should get at least 600W PSU. If they run at current close so their max ratings the components degrate and will fail lot sooner compared to componenets that were not stressed all the time. There is also stability issue when PSU runns close to its rated power.

 

So really you should never go cheap on the PSU, it should always be of good quality and you should always have more power then you "need" ;)

[Bolt-1]

.... or use 2 PSUs on 1 PC :music_whistling:

 

without going into details. Tried it. I'ts not worth the time, effort or trying to save money just cause I had two extra PSU's lying around. :doh:

[cichlidfan]

without going into details. Tried it. I'ts not worth the time, effort or trying to save money just cause I had two extra PSU's lying around. :doh:

 

Especially since two mediocre power supplies are still not going to make one good one.;)