PC Peripherals Why are we obsessed with high power PSU's ?

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vinayaga

vinayaga

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I have been thinking a low about saving power recently and built a device similar to "Kill a watt" to measure how much power is being drawn by each item in the house. :clap:

When I used the same on the computer, I got some interesting results. I have a Quad core Intel with a Radeon HD4850 card, 4gb mem, two hard disks, two DVD Writers and a Soundblaster PCI card in the system. On idle, the system draws a total of 125W. On playing Crysis with all settings at high, I get a peak usage of 220W. Even with a full CPU load, I never cross 280W. Granted I have a bronze certified Antec PSU that is very efficient, but even a inefficient PSU will draw another 15% more.

When I tried the same test on another older AthlonXP 1700+ CPU + motherboard + 1 DVD Drive + 1 Hard disk system, I got a usage of 110W with a very old PSU. When I tried this same system with a good PSU, I saved another 10W. And finally when I tried the same system with my Antec Bronze certified PSU, I saved 20W compared to the first PSU.

So the difference between a Bronze certified PSU and ordinary PSU found in every shop in India is a max of 20W. Which means that if I run the machine with a bad PSU for 50 hours, I end up saving 1 unit of power (Rs 5.xx at the peak slabs) :huh:

In other words, with a fairly high end systems, Im drawing less than 300W at any point in time with any PSU. A bronze certified PSU gives me a saving of Rs 5 every 50 hours.

Based on these results, all we need is a 400W PSU that can handles spikes and fluctuations well. Why then the fascination for expensive 480W plus and 600W Bronze certified PSU's that are recommended in every thread in every forum ?

What am I missing here ?
 
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very good observation vinayaga . I've been trying to get a device similar to "kill a watt". Can you tell me where to get same for 220 volts ?
 
Just to clarify. Are you measuring the power drawn from the mains? Or the DC power drawn by your peripherals?
 
^ if his device is like "kill a watt", he is measuring power drawn from mains. But let vinayaga comment on it
 
1)Irrespective of the amount of power saved, a High quality PSU will always be recommended in tech forums because of the pure/clean power these branded PSUs deliver to ur PC components, which IMO, is the priority to most of us.

2)We have seen instances where even CoolerMaster PSUs have failed to deliver even 75-80% of their rated power and gone kaput, taking a toll on ur PC components as well....so its always better to keep ample headroom.

3)Enthusiasts and overclockers do justificably need more power.

4)A 4850 and a quad aint really a power guzzling monster to begin with, folks with bigger and better video cards need better PSUs. Not necessarily of high wattage but high quality and reliability for sure.

5)For folks who upgrade frequently, a one time investment in a better PSU serves well over the course of a few upgrades.
 
Interesting thought. Please let us know more about how you are measuring this so that we can follow it and but an appropriate PSU rather than buy something just because the so called 'experts' say its the best.

As someone mentioned above please let us know where you bought this.
 
I did not buy it, I made it myself as I was obsessed with it and "kill a watt" was not available for 220v countries ! Spent a grand total of Rs 700 and it is very safe to use. It basically measures the total amount of current being drawn from the wall socket.

It is very easy as long as you know what you are doing. I will post some pictures along with step by step instructions when I get home in the evening.

[Edited] Here is the link for the DIY kit : http://vinayaga-raman.blogspot.com/2009/08/kill-watt-for-220v.html
 
@OP - Its not that people are really obsessed with high power PSUs. Its more the obsession with high "quality" PSUs. There's a difference there (quite apart from the efficiency)

In addition to what mithun said

(a) Better quality of components that go into building the PSU meaning they will (probably) last longer
(b) A cleaner "ripple free" DC supply
(c) (Usually) higher warranty cover
(d) Less noise levels (important to some people)
 
I think his main question is regarding the High-Wattage recommendation, not High-Quality.

Even if you take 400W as magic number for max floor value, for regular setups... having 400W PSU doesn't mean that it will always deliver 100% of advertised wattage. A generic, local-brand 400W PSU will deliver typically 60-65% (240-260W), a good decent brand PSU will deliver around 75-80% (280-290W), a high-quality PSU with 80+ certification will provide you max 85% (320W). So if you're looking at achieving 400W, you're basically looking at a good PSU which will deliver you 400W at maximum efficiency (80+)... somewhere around 500W PSU. But like I said that is if you're looking at 400W as magic number.

But that's not end of the story there, beside the wattage delivery, there is question of quality of component used, build quality, noise, cooling efficiency. Higher quality of component deliver clear current with less fluctuations, better cooling helps increasing component life etc.

So in that sense, most of the rigs with decent (read: higher-mid-end) graphic card, should not require more than 480-500W PSU... given that the PSU is good quality and is 80+ certified. Of-course, those who want multi-gpu setups, or high-end graphic cards and/or exotic cooling setups like liquid cooling or Peltier based coolers, they will require higher-watt PSUs.
 
I agree with most of what Mithun and Vulc4n have to say. But most of this applies to the high end systems and enthusiasts out there.

Frankly speaking, the percentage of the PSU blowing up is medium rare, but it taking the system components with it are very rare. I have had three PSU's blow up in 18 years and all times none of the components were affected. You will read about these cases once in a while, but remember that the percentage of unhappy people reporting this in a forum is way way higher than the folks who will tell you that nothing happened when their PSU blew up. So there is a lot of perception out there that components are expensive and you need clean safe power to get it working.

My problem is mostly with the fact that in every old thread that I read where a clueless newbie with a basic core2 processor and HD4670 is asking for a PSU recommendation, folks start with nothing less than a Corsair VX 450W and then beat up every suggestion of a lower priced PSU which might work just as well for that system. That is why I used the term obsessed !!!
 
I would like to hear some specific recommendations from you on which PSUs can be a suitable alternative, and hopefully someone can try those out. I see only a rant against opinions that advocate quality components. If you have heard of, tried and tested options that meet your criteria of a

PSU which might work just as well for that system
Click to expand...

I'd like to hear it.

Show me one 80+ 300 watt quality-built PSU that is available for cheap, and I'll recommend that instead of the Corsair or Antec PSUs.

If you look at efficiency and performance, the sweet spot for most PSUs is between 50% and 70% of rated load. This is similar to your car, where the sweet spot is in the midband, between efficiency (mileage) and output (horsepower). This is pretty apparent from most PSU tests.

For a system drawing 200 watts peak (which represents most common systems) you need a PSU capable of 300 watts peak load. It will run on a PSU of 230 watts, but that is asking a donkey to run the derby. And apart from the Seasonic 300 watt unit (not available in our country) there is simply no unit like that. Unless you count the 'Extreme' Power series, of which the less said the better.

There are secondary issues - ripple, regulation and protection being among them. I've seen supplies with 200mV ripple on the rails, I've seen supplies burn out connected wires and not shut down (fire hazard for sure) and I've seen one particular take out a 6600GT and a hard disk when it went down. The quality of the supply is very important, and that is why the VX450 (for example) scores high - there is not a single unit out there today that can compete with it on complete peace of mind.

It is future-proof (almost), can take massive overloading for short term running, and is stable, quiet and totally protected and it comes with what is a very long warranty by any standards, longer than anybody keeps their systems.

And your personal experience of PSUs blowing up is no indicator of a statistic. Expand the survey to a thousand users (not on TE, that would defeat the purpose) across multiple cities, and then we have something to talk about. I have lost three PSUs myself in about the same time, but mine have actually taken out components. I'd rather not take those chances, or reduce them as much as possible. I have only Corsair and Seasonic-built Antecs in my systems now, and have no fear for my components or data. And these are not all high-end or enthusiast systems, one is a daily-use DL rig, one is a music rig, and only one is a gaming rig with high-end components.

Of course, if you want or want to advise people to play Russian roulette with their systems, please go ahead. At the end of the day we only advise, we can't choose for the people asking for advice. You should throw in your two cents, stir up the pot, and see what happens! :) It is possible to run systems with generic PSUs. It's just not the safest or the wisest thing to do.

And there were alternatives, some of which were well recommended. I remember distinctly recommending the Powersafe silver series PSUs for generic rigs, then obviously the company had to discontinue it and introduce something with lower specifications and sell it at the same price point as the older unit. The new units are not worth half the money you end up paying. As of today, there is not a single alternative at the low end of the ladder, it's just a game of margins so the PSU manufacturers end up skimping on parts and circuitry.

At the end of the day, as with everything else, you get what you pay for.
 
1. I agree with vinayaga's observation as I have also seen the same trend here. In fact I have seen instances of guys suggesting VX450 for simple rigs with onboard gfx when they themselves are using a bundled iBall type PSU for months and have tentative plans to change to VX450. Not that I personally advocate using the bundled PSUs but a VX450 for E5200+G31M S2L and no gfx card? We have the Zebby Pro, the Superb 460 and the Seasonic 380W which must be considered as more cost effective options.

2. iGo's analysis is faulty because his understanding of power rating and connecting it to efficiency is wrong. The two are unrelated. The main indirect connection that efficiency has is a) a higher efficiency PSU will have less internal heating and consequently may be expected to have a longer life and b) a higher efficiency PSU will be expected to be of better design and hence more reliable. But these are both just expectations.

3. I have no clue what "Kill a watt" is but going by what vinayaga described, that is a completely wrong measurement of input power. One cannot just measure the input current and multiply by line voltage to arrive at input power. Many people talk of power factor but the fact is that power factor is relevant only when the current waveform is sinusoidal. Take it from me, the input current of a typical SMPS is far from sinusoidal. The only way to measure true power is an actual vector product of voltage and current and those instruments are not cheap.

I am not qualified to speak on the kind of current waveform when the PSU employs active PFC. If that indeed corrects the input current waveform along with PF then vinayaga's method may work to some approximation with such a PSU only.
 
When the whole forum suggests VX450W, its called collective experience. Just because your Generic PSU didnt take anything down with it doesnt mean we should all recommend it. And we do not force anyone to buy anything. We only suggest products which have been tried and tested by either us or many others in the forum itself.......
 
Cranky is bang on in his argument. There are cases where PSU takes out video card, no point in risking a 15K card for a 3-4K for PSU.

That being sad, system stability is a huge factor. Half of my system un-stability issues were eliminated by VX450 as compared to a 400Watts VIP gold PSU. Infact a good PSU has become a priority when I buy a new computer, or recommend one to anyone. I can compromise on other components but not the PSU anymore.
 
Don't have source but remember reading that power supplies would be at their peak efficiency at ~60% of their load capacity i.e if your system were to take in 100-200W idling and 300W on load,what you'd need is a decent,energy efficient(80+) 500W PSU. IMO a 600-650W PSU would be more than enough to handle every enthusiastic rig configuration possible save for those having SLI/X2 configs .Even then I'd say 800W is more than enough.Why somebody would use 1KW and above is beyond me.
 
@vinayaga: Really a good observation and topic - even I was thinking on writing something on this topic - but my take was just opposite and its from my first hand exp.

--

RECAP:

I got a sapphire 4670 and getting vpu error- pinged here- suggest for a psu change> I got a corsair 400cx - which is a overkill to my current requirement; still the vpu error persist and RMAed the card for 4670 was not in stock ; they offered 4850 - I go for it - only because I have the enough psu to handle it and also upgrade my rig.

I got 400cx considering suggestions which says "future proof" and thats what it is ? I don't want to put around 1-2k for a time being and going for another change for 1-2k or more for a new psu to support my upgrade or feel handicaped (shying for a upgrade). I understand; not everyone need a future proof and not all suggestions are mean for that. Some just suggest the most popular brand/product and some actually suggest + explanation why it is going to be beneficial.

As a techforum we all try to help-educate-level up people from generic users to power users.
 
>> For a system drawing 200 watts peak (which represents most common

>> systems) you need a PSU capable of 300 watts peak load. It will run on a

>>PSU of 230 watts, but that is asking a donkey to run the derby.

Maybe my point did not come across. The numbers I mentioned are the amount of current drawn by the PSU from the plug point. How it is used, how much is wasted and what is done with the power drawn is immaterial here. The PSU draws a max power of 250w from the mains, probably wastes 20% of it and the computer uses the remaining 80% (So the computer needs just 200w). So a 400W PSU would be more than enough even in my case.

>> Show me one 80+ 300 watt quality-built PSU

And this was my second point ! Why is the 80+ certification needed at all ? A moderate PSU wastes say 15% power, that translates to losing Rs 3-5 per fifty hours of usage. That is not more than Rs 25 per month if you run the computer for ten hours a day. It is a insignificant saving for a big upfront difference for a bronze certified PSU.

>> Expand the survey to a thousand users (not on TE, that would defeat the purpose)

>> across multiple cities, and then we have something to talk about.

Think for moment about how many computer users actually assemble their own machines knowing what they are doing. And how many computers actually end up running the latest and greatest components that money can buy ? And then think of how many people walk into a shop and ask for a assembled computer with a good processor, high memory and big hard disk (Believe me, this is all people ask for when they want a computer) at the lowest price. The local vendor gives a damn for a good PSU, he knows that if he quotes Rs 500 more than the computer assembler next door, he loses the order. These computers spread all over town would outnumber the ones with good PSU's 1 to 1000. And how many of them fail and burn ?

I appreciate all the points about good quality and steady current and all the other arguments that people have put forth. My point is only this, we should not confuse the guys who can afford just a Zebronics or a iBall SMPS and are coming to TE to see what is the best they can get for their limited budget.

Believe me, I have nothing against good PSU's, in fact I just moved to a Antec after joining TE and reading half the forums. But since I read so many hundred threads in a short while, I got the distinct impression that the recommendations for a PSU always seem very high end in TE. Hense the thread and question.
 
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