I heard that the electronic components in a computer only draw the amount of current they are set to draw, so if I bought a powersupply with more wattage than I need it wouldn't hurt.....is this true?

The reason why I'm asking is I bought a 500watt powersupply for me computer which is:

5 LED 80cm fans
AMD 650 Athlon with 384 MB of Ram
1 60 gig hard drive
1 200 gig hard drive
2 250 gig hard drives
1 CD RW burner
1 DVD RW burner
1 Promise Hard drive PCI card
1 Turtle Beach Santa Cruz sound card
1 ATI all in one Wonder 64 mb(it's about 4 years old)

Do you think 500 watts will be to much or does it matter because of the theory above?

Thanks,
darin

You don't need 500 watts to power this computer, with less could run perfect.
But think that if some day you upgrade your machine or plan to install some cards you can need this extra power.

It is way overkill. There is some loss of efficiency with getting higher wattages than you need, so more wasted power. But this is compensated by higher rated power supplies being built more efficiently, so it's probably a wash.

You would have to buy a quite extreme system to draw 500 watts.

In practise, you can do with a lot less even with some more upgrades. More than say 300W is seldomly needed for a single CPU system. It's much more important that the power supply is of high quality, so that it actually delivers the advertised wattage, instead of a fraction thereof.

I am with Garf.
I suggest an Antec or Sparkle power supply. Both brands have a very good reputation over many years.
I recommend at least 350W these days. With all the hard drives and fans you are running, a 450W seems a minimum.
Having more wattage than you need is like having a larger engine in your car than you need. If you need it, the power is there. If not, no worries.


Edit: The graphic cards these days are getting REALLY power hungry, sometimes needing an external power connector. If you upgrade your graphics card in the future you could easily need more than 300W.

Yes it does matter.. In switching power supply.. If you drain the power supply too much.. that is the power requirements nears the max power output of the circuitry.. the regulated output will become unstable.. or noisy.. or spiky.. That is why it is a usual practice to have a large safety margin..


wkwai

..and thats also why it's better to have a GOOD power supply rather than just one with a large wattage. All high end power supplies will still have excellent characteristics near full load.

I disagree strongly. More than 300 Watts is almost never required if you do not have a dual CPU system.

WORST CASE P4 >3Ghz consumption = +- 110W
WORST CASE Nvidea 6800 consumption = +- 100W
WORST CASE 4 HDD = +- 60W

Power consumption of most other components is relatively minor.

Even with the most power hungry components running all at worst case (completely unrealistic in practise), you will not be able to exceed 300W drain. It's been observed that the typical consumption of such a system even in heavy gaming does not go over 200W.

Note that this does not apply when the power supply is so crappy that it gets unstable output running at half its load. Most reported PSU related problems come from this, not from "magical" systems that draw over 300Watts.
So I'll repeat what I said: it's much better to have a good 300W PSU than have a crappy 500W one.

Additionally, note that newer Nvidea cards are lowering their reported worst case power consumption, and the same is more or less true for new CPU's. At some point the heating becomes a problem so one cannot make the components much more power hungry.

I tend to agree with Garf, as my computer (P4 2GHz, 2HDs, DVD-reader, CD-writer, nvidia geforce 2MX 400, two soundcards, tv-card), is powered by a 250 watt power supply and runs like a charm. If you have a more demanding video card or CPU I can image you may need a more powerful supply, but anything as high as 500 or 450 watt seems pretty extreme to me.

With a count of:

5 fans
4 hard drives
2 cd/dvd writers

I stand by my recommendation of 450 to give room for growth. You could probably get by with 400. I will look up some links to substantiate this.

http://www.amd.com/us-en/assets/content_ty..._docs/26003.pdf

This chart indicates about 28 watts per HD.
15.6 watts per cd burner.
3 watts each for system fans.
30 watts for 128 mb ram. ( that would be 90 for 384 )

It is kind of like ram or hard drive space. It is hard to have too much.

If I do the calculation by that guideline (which has worst cases, e.g. current drives generally use 15 watts not 30 watts!), I still only get+- 350Watt. And this for a system which the most power hungry CPU in existance, the most power hungry graphics card in existance, and a shitload of components all running in their worst case situations being all fully loaded at the same time.

You won't even get close to it in real conditions, let alone with anything less than this hypothethical worst case system.

And as noted above, "overkill" PSU's do waste energy, so there is a point in not getting 200Watts over what you really need.

Just for future reference, how many watts does a shitload consume?

Edit: Punctuation

Has anyone heard of the Coolmax brand? I was thinking about getting one becuase they don't cost an arm and a leg and seem pretty nice....


-Dman

Some of that are not real-world figures. Current 7,200 RPM hard disks use below 10W. 384 MB RAM don't use three times the power as 128 MB; it's more per module than per capacity. There's not terribly much difference between 2x 128 or 2x 512 MB.

Here we have some power consumption charts of the following system with different graphics cards:
CPU Intel Pentium 4 3.2 GHz
Motherboard ASUS P4P800 Deluxe (i865)
Memory 4x Corsair CMX256A-3200LL (TWINX)
HDD Seagate Barracude 7200.7 120GB S-ATA (8MB)
DVD Hitachi GD-7000
LAN Netgear FA-312

http://graphics.tomshardware.com/graphic/2.../gddr-3-11.html

Average consumption under XP, idle: ~112 W
Average consumption under XP, full load, 3D game: ~200 W

That's for a pretty high-end system there. I have such an "energy check" device myself, and for my second PC (P3 1.13, 512 MB RAM, 2x HD, TNT2 graphics card, sound, LAN, CD) i get 65 W idle!

Thanks Citay, I hadn't yet looked for the graphic card link. They are hungrier than I realized.
I was also surprised when I visited the Seagate and Western Digital sites.
As Citay said, the 200GB drives are using around 8.8 watts, less than 10 for sure.

Other than the method used by Tom's Hardware (full system consumption), the guys at X-Bit Labs managed to measure the power consumption of the graphics card only, resulting in this graph:

http://www.xbitlabs.com/images/video/ati-v...i_vs_nvidia.gif

Full article at http://www.xbitlabs.com/articles/video/dis...s-nv-power.html

No card comes close to 100W under full load. Even with a high-end system that needs 150W on it's own under full load, you won't be able to reach 250W total consumption with the most power-thirsty graphics card. A 350W PSU should handle that with ease. The only people that would need 500W PSUs are those with compressor-cooling + highly overclocked system...

edit: Their server is overloaded at the moment, so i attached the graph...

I checked out the Antex Neo power and for a 400w they want like $125.00, so I am favoring the Coolmax for the ratio of qaulity and price(with a single fan/low noise).

On the powersupply I want to get, Coolmax, these are the results from a review I read:

These readings are at max load using a 3ghz cpu @ 3.8Ghz

Item: Results
+12v 11.80V
+3.3V 3.20V
+5V 4.97V


Are these good readings for a the 500W PSU that cost $67.00?

Thanks,
-Darin

Funny how you brush it under the carpet that you don't ever need a 500W PSU

Well, the readings are within the ATX Specs (p. 12), even though the 3.3V line is a bit on the low end there. But most PSU reviews are oversimplified anyway. Just looking at the voltages in a monitoring program doesn't say much about a PSU. When you saw a PSU test of german c't magazine, you see what most others are lacking; you need to take into account the degree of efficiency, power factor, voltage constancy, interference immunity (blackout, surge, bursts, impulses), noise, heat, all at low load and full load. If you don't have the devices to test that, then you get a common internet review like "the cables are really long, and the PSU looks so shiny. voltages look great in MBM. gold award, 9/10."

If you must .....


Antec 430W Power Supply, Model "TRUE430" -RETAIL

That is the problem.. from where I came from.. I think most power supply are rather "standard".. cheap low quality type..

I am aware that there are some types of switching power supply that can cost thousands of dollars, designed specifically for highly sensitive electronic equipments such as telecommunications radio systems etc-etc..

As far as I knew, most PC type of power supply over here, South East Asia aren't of that kind of grade

wkwai

You also need to consider from where you want to draw the power. For example you may be able to draw 30A from the 5V line and 20A from the 12V line which would be a total of 340W. Nowadays most components draw power only from the 12V line so you basically lose 150W.

Of course this is simplified, but you get the picture.

Brands which I would recommend are "Enermax" and "Be Quiet!".

Take a look at Power Wattage Calculator (sometimes it doesn't load, so here's a Google copy - works too). To make it show the correct value, first select the stuff with check-boxes & radio-buttons, and the stuff from combo-boxes (CPU, GPU, and memory) at the end.
And a neat review of some PSUs, it's in polish but the tables are pretty self-explanatory.

What about Seasonic Powersupplies...I heard they are supposed to be really good and top notch qaulity. Is anyone into them?

-Darin

I like my Nexus NX-3000 very much, it's silent and powerful enough for my fully equipped xp2400+ pc. Good quality and reasonable priced (about 45euros)

Some very good reviews:
http://www.silentpcreview.com/section4.html

As we are now in HA, I think people would appreciate that their computers are not the main source for decibels in their homes....

Seasonic and the Nexus are both okay, according to a c't review. The Nexus failed the Bust-test repeatedly between 1.1 and 1.2 kV, but for home use it's sufficient, because the european norm only requires 1 kV burst resistance (and 2 kV for industrial use). Cheaper PSUs were seen to fail completely at 1 kV already (Safeforcer, Coba, King Yes..). Other values of the two are ok.

I am thinking about getting a power supply unit, but I can't tell if it's PFC is active or passive. Here's the spec's:

SPECIFICATION
Active PFC: 0.95@230VAC; Passive PFC: 0.7@230VAC With +5VSB: 0~2.5A Max.
AC input 100~132VAC or 200~264VAC
Frequency 47~63Hz
Efficiency >75% at full load
Meet FCC part 15 Class B, CISPR 22 Class B
Designed refer to UL, CSA, TUV, CE regulations
Meet Intel ATX12V/ATX 2.03
Dimension: 150x140x86 mm


I never heard of a PSU being both, so can anyone else tell from this?

Thanks,
-Dman

What's the model?

Here's the link:

http://www.coolmaxusa.com/products_powersupply.asp?item=29

I was going to get the CR-450W(decided to compromise with myself and get a 450w instead of 500w). I wanted to get the Seasonic but I decided that I should be carefull on spending to much money....

For your setup, a 250W model would be sufficient... but 300W ones are easier to get these days.

About the PSU you linked to, i've never heard of Coolmax before... they state things like "Efficiency >75% at full load" which says nothing, cause it much more depends on efficiency under low load, like what will happen 99.9% of the time with your setup. I'd say you won't even be using 1/6th of it's capacity if you buy that.

Yeah, I can't help it though. I love the idea haveing all those extra watts sitting on the side ready to be used if ever needed(even though they won't be). Plus, someday I might upgrade my computer...of course by then I bet the PSU's with active PFC's will be alot cheaper.


-Darin

Well, that's a valid thought, but since you can basically run any high-end machine with a good 350W PSU, i don't understand people who pay a lot extra for 500+W PSUs if they don't even overclock or whatever.

Also, there might be some confusion over PFC here. PFC does not mean efficiency. An efficiency of 75% means, if the whole PC draws 100W, it really only needs 75W, and the 25W come out as heat from the PSU. The best efficiency is reached at high load. For instance, at very low load (standby mode), a PSU has maybe 10-20% efficiency, meaning that if it draws 10W, then 8 to 9W are going to waste as heat. Of course you pay for all that, heat or not, so you need a) a PSU that generally has a high efficiency, and b) have one that's not way too "big" for your PC, cause you'll be wasting more energy that way.

PFC (active or passive) is not of major concern for yourself; contrary to efficiency, it doesn't affect your electricity bill. It's only there to make the "shape" of the drawn power more sinus-like. As depicted in the screenshot i'll append, switching power supplies normally draw short bursts of power, which has negative side-effects for the power providers. To solve that, passive PFC uses a simple inductor which restricts the slope, and active PFC uses a HF transformer. Since every PSU needs to have PFC these days, there's nothing to it, and it's certainly not a selling point. Again, for you, it's irrelevant if it's passive or active.

Hey CiTay, my power supply is bigger than your power supply.

Mine exactly matches the ATX size specifications

As far as I know:

- here (and in the rest of Europe) PFC is mandatory
- you can get extra charges on your electricity bill if your inductive load is too big (which is what PFC corrects)

So it certainly *can* affect your electricity bill.