Please satisfy my curiosity - PSU question

[Waco]

For some reason I got into an argument with someone on another forum (I should know better than to argue with this specific individual...he's essentially the combination of sack_patrol and your average spammer) - suffice to say he's trying to use answers from pureoverclock.com (hah!) to back up his misrepresented argument.

 

I won't misrepresent it here - but I do want to ask a question:

 

 

If you have a rig that pulls perhaps 300 watts (maybe with upgrades to pull it to 450 watts in the future) would any of you seriously advocate buying an 850+ watt PSU?

 

 

His reasoning is that bigger is always better with no regard for efficiency, cost, or anything.

 

My reasoning was that buying more than you need can be good to a certain extent - but going beyond your needs by a couple hundred percent is pretty useless and wasteful.

 

 

Thoughts?

 

 

EDIT: Since potatochobit is trolling and I'm stupid enough to take the bait; here's some clarification:

 

All the PSUs suggested are of good quality. Yes, we know that 12v amps are far more important than any other spec in a modern PSU. The 300 watt figure above is with the CPU and GPU loaded with Linpack and Furmark, respectively.

Edited March 16, 2011 by Waco

[Gr4vitas]

Yea in a theoretical situation like say your going to use (tops) 200w and maybe you'll make upgrades to 350w in the future (like a year down the road) spending a bunch of extra money getting 200% the wattage you need is ridiculous.

[SpeedCrazy]

I agree with you. I would buy more than i need to get maximum efficiency but that is ridiculous.

There must be a point beyond which it is damaging to use to little percent as it is not pulling enough to get moving and efficient. (just my uneducated cohesive idea)

[potatochobit]

you are both incorrect, Peak wattage is not the most important spec

it is the amps on the 12v

if the PSU costs less than 50$ the higher the wattage the better, at least we hope it may be better quality

 

edit: sorry it's called peak, not max

because I know u gonna cry about it

Edited March 16, 2011 by potatochobit

[Waco]

you are both incorrect, Peak wattage is not the most important spec

it is the amps on the 12v

if the PSU costs less than 50$ the higher the wattage the better, at least we hope it may be better quality

 

edit: sorry it's called peak, not max

because I know u gonna cry about it

Do you really have to troll everything? This discussion has nothing to do with "the most important spec" it's about whether or not you should spend as much as possible to get the biggest PSU possible regardless of the actual load you put on that PSU (I say more is better within reason, he says more is always better).

 

With any decent quality PSU in recent years the majority of the wattage is on the 12v rail anyway. If you want me to refine my argument:

 

Which is better advice:

 

The computer uses 20 amps on the 12v rail with the intention of using ~30 amps in the near future.

 

I say he should get something in the ~40 amp range to run in the efficient range of the PSU.

 

The other guy says it'd be worthwhile to buy something that has 70+ amps or more on the 12v rail because more is always better.

Edited March 16, 2011 by Waco

[potatochobit]

the other guy who said 70a was correct, the rest of you were wrong.

 

You may not have given out much advice on power supplies lately but I guarantee you that 9 times out of 10 if someone asks should they buy a 650w power supply or an 850w power supply they are talking about the cheapest 39.95$ C-mart brand power supply they can buy.

 

now to put it simply, it is generally accepted that you would get a power supply that is 200W over your need. this ensures some future proofing for upgrades and add ons. some people will even say 100w is enough.

 

so if your friend is pulling 400w at the wall, he needs a 650w supply, an 850w is ludicrous unless he has definite crossfire plans.

[Waco]

the other guy who said 70a was correct, the rest of you were wrong.

 

You may not have given out much advice on power supplies lately but I guarantee you that 9 times out of 10 if someone asks should they buy a 650w power supply or an 850w power supply they are talking about the cheapest 39.95$ C-mart brand power supply they can buy.

 

now to put it simply, it is generally accepted that you would get a power supply that is 200W over your need. this ensures some future proofing for upgrades and add ons. some people will even say 100w is enough.

 

so if your friend is pulling 400w at the wall, he needs a 650w supply, an 850w is ludicrous unless he has definite crossfire plans.

I don't even know why I respond to you...you didn't even read what I posted. That said, the rig in question uses 300 watts at the absolute maximum (that's with max utilization on both the CPU and GPU, IE: linpack and furmark). The user has aspirations of adding a second (perhaps third, though unlikely) GTS 250 to bring the total to roughly 450 watts give or take a bit. I suggested that 850 watts was crazy overkill (especially given his current power draw) and he'd be fine with a quality 500-550 watt PSU.

 

Now, can you please restrain yourself from trolling any more? Acting like we are all completely ignorant isn't helping your argument.

Edited March 16, 2011 by Waco

[Crazy_Nate]

So, the question is...

 

Where does the efficiency curve peak? And where does your typical usage lie? That'd be my starting point for sizing a PSU

[broooooooce]

There's a pretty thorough debate about this topic here: http://forums.overclockersclub.com/index.php?showtopic=182247

 

One of my biggest pet peeves is people who subscribe to the incorrect belief that higher wattage = higher efficiency. There's tons of links and support for your argument in that thread.

[Waco]

So, the question is...

 

Where does the efficiency curve peak? And where does your typical usage lie? That'd be my starting point for sizing a PSU

I would assume that most PSUs follow the trend of being pretty horrendously inefficient at <15-20% load.

 

This guy is advocating a PSU so large the computer will barely break 30% draw on the PSU with the most extreme load possible. I would assume that 95% of the time it'll be sitting roughly in the ~10% load range.

 

 

There's a pretty thorough debate about this topic here: http://forums.overclockersclub.com/index.php?showtopic=182247

 

One of my biggest pet peeves is people who subscribe to the incorrect belief that higher wattage = higher efficiency. There's tons of links and support for your argument in that thread.

I do believe I was arguing the opposite point for a while in that thread. Higher wattage does lead to higher load efficiency though.

 

This is more of a question about the extreme - bigger always being better, that kind of thing. I completely disagree with the notion that bigger is always better (especially in this case).

Edited March 16, 2011 by Waco

[Andrewr05]

lawl

 

 

I agree, I would rather stay within 100-200W of what my maximum will be.

Spend a good amount of money on a decent PSU within a certain margin of watts and a decent number of amps.

 

 

Some may argue though that you could then drop this PSU at a later date (years down the road) if it was an overkill PSU into a newer PC, but who knows what systems will draw power wise in 5+ years?

 

or if new specifications, power pins or even form factors will come out in the next 10 years?

[Waco]

or if new specifications, power pins or even form factors will come out in the next 10 years?

Or if your 5 year old PSU can even produce the same amount of power as when it was new without failing.