PSU Myths

[CGR]

Thought this was a good article.

http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3413

[eatdirt40]

Sure is. That is why I use a 400watt power supply.

[Enablingwolf]

When you overclock and overvolt. It throws out all them figures.

I know my modest machine. Which is overvolted and running a lot of fun things. Will suck up much more than what the myths article will give info for.

What about my four hard drives .. Lights and fan controller? I do have more than just a few fans. Though they are running low voltage. I give all this about a 100 watts leeway by itself. Overkill. But I do not want to go near the top end of what power my machine (better yet PSU) can handle. I got led fans, leds and UV for when I want to make the machine look purdy when company comes over. All the drives I have are function.

Good guide for those who run regular machines.

[CGR]

When you overclock and overvolt. It throws out all them figures.

I know my modest machine. Which is overvolted and running a lot of fun things. Will suck up much more than what the myths article will give info for.

What about my four hard drives .. Lights and fan controller? I do have more than just a few fans. Though they are running low voltage. I give all this about a 100 watts leeway by itself. Overkill. But I do not want to go near the top end of what power my machine (better yet PSU) can handle. I got led fans, leds and UV for when I want to make the machine look purdy when company comes over. All the drives I have are function.

Good guide for those who run regular machines.

What are your current system specs?

Also, I think the point the article is trying to make is, you dont need a 1kw PSU when a 700 - 800w will be more than enough.

Lets assume your system is close to performance of their performance setup. That took 544w under load. Now add your extra 100w for all you mentioned and you have 644. A 750 - 800w unit would be more than enough and still give you a little room for additions. you just wouldnt needa 1kw unit.

Keep in mind that their performance setup had two 8800 ultras in it. Its a shame they didnt add info for newer cards..

[dribblesnort]

I wasn't all that impressed with the article...It was informative, but to a far smaller degree than I am used to seeing...

[WonderingSoul]

To us, the people that know about PSUs, this article may not be spectactular.

To the PSU ignorant, I think it's a gold mine.

[Enablingwolf]

Keep in mind that their performance setup had two 8800 ultras in it. Its a shame they didnt add info for newer cards..

I did like the article. That is the thing. It is really hard to judge what is going on in each system. I will spec my rig out lower down. I hold to the same thought as the article. But with one twist.
Knowing the basics and using it to have a bit of extra. Even if you buy a 1Kw PSU. It will not use more than the draw. Knowing the direction of machine later on, that will use that much. Is a good way to use the misused term 'future proof'.

I use a crappy to works ok OCZ Modstream 450. I know what it can do and its limits. I will say it is so-so to average. The 5v rail hates me.. I known that for years.

Ok you did ask me about y specs. That Iwill five. But first... What machine do you want the specs on? I will spec out what it is probably going to end its life in. Not what it has powered for me in the past.

UV light kit. That I have tinkered with It is not one tube.
Four fans that have LED- 3 have full on UV. One other fan is painted, but is black. So 5 fans.
Drives.. - 2 7200 and 2 (74 AFA) Raptors. Two DVD ROMs
Sunbeam fan controller.
LED display, which is really cool..
Sometime I pop in the cards. It depends what I want out of the hardware. There can be two of these.
nVidia 7300GS BIOS modded and overvolted.
E2200 overvolted and overclocked.
Few other tid bits.. But not worth mentioning. Sicne they are ... pulling of the USB and other ports. .. Yes, have to accoutn for USB and Firewire...

Does this answer yer question bro? :D

Oh, my calculations. I pull past 425 watts.. IF!! I do a everything at once.. It is going to 600 watts. That is pure.. not in lets only do one thing at once... None of the plug in my many players.. and such.. Just simple being lazy and two tasked goal.

If I put my DDM to the task. It will tell me if a rail is lagging behind. Which makes heat. In turn. Makes a PSU less efficient.

[cyberfish]

I am PSU ignorant and it is indeed a gold mine :).

So my system with E6300 (overclocked, assuming 60W) + 9600 GT + P35 + 1 HD + 1 optical + 4x1GB RAM only draws 245W on load.
I am not sure if they included fans and such, so I will assume they didn't. I have 3 fans in my system including the CPU one. One of them says max 0.35A current draw, so I will use that.

3 * 12V * 0.35A = 12.6W

For a total of 257.6W. So I guess my 380W Antec EarthWatt that I got for ~$25 is an overkill for it :).

BTW, I love how they have 3870X2 and a quad in the mid-end system... guess my overclocked E6300 + 9600 GT has to be low-end... damn :).

[eatdirt40]

I am PSU ignorant and it is indeed a gold mine :).

So my system with E6300 (overclocked, assuming 60W) + 9600 GT + P35 + 1 HD + 1 optical + 4x1GB RAM only draws 245W on load.
I am not sure if they included fans and such, so I will assume they didn't. I have 3 fans in my system including the CPU one. One of them says max 0.35A current draw, so I will use that.

3 * 12V * 0.35A = 12.6W

For a total of 257.6W. So I guess my 380W Antec EarthWatt that I got for ~$25 is an overkill for it :).

BTW, I love how they have 3870X2 and a quad in the mid-end system... guess my overclocked E6300 + 9600 GT has to be low-end... damn :).

Yes, but another factor people need to understand is that the 380Watt Antec Earthwatt PSU may be overkill, but the PowMax 380Watt isn't....

[theELVISCERATOR]

put a wattmeter between your system and the wall and know for sure.

Are they testing under full load also... I see an amazing spike in AM3 during the final explosion for example...with a meter running...

[Vengance_01]

The Article brings up a great point, you don't not need these huge power supplies for 99% of computers. A solid 500-600 Watt unit is still plenty and mostly overkill as it is.

[theELVISCERATOR]

Well I am sure my system would flat blow a 400 watt psu..rofl..

[Super Nade]

There is no mention of how the measurements were taken or what kind of programs were used to stress the system. In my experience Fur and Linpack run together will most likely be among the most stressful software combination.

[Mr.Guvernment]

q6600 @ 3ghz
4850
6 harddrives
Zalm s9700
LG DVD Drive

Even though my corsair 650w PSU has 3 SATA power connectors on one chain and has 2 of those, if i have 6 hard drives connected - it boots and shuts down, i had to move 1 HD off to a 4pin to SATA adapter :(

[Super Nade]

Odd. Since the unit is a single 12V rail one, I do not see why this should make a big difference?

[muddocktor]

Some other things that article doesn't take into account is the fact that you don't want to run your psu right to the edge of it's power envelope either. Your psu will have it's best efficiency at between 50-75% rated load and also it will run much cooler than when a psu is running close to it's max power output. This means the psu has a much better chance of lasting longer since the components aren't stressed nearly as high. And it also doesn't take into account at what temp the psu was rated at. With quality units like the Corsair psu's, they are rated at 50 C, but IIRC the PCP&C Silencers are rated at 40 C. And many others are rated at 25 C, which is just a plain unrealistic temp to rate a psu at.

[Blazing fire]

What are your current system specs?

Also, I think the point the article is trying to make is, you dont need a 1kw PSU when a 700 - 800w will be more than enough.

Lets assume your system is close to performance of their performance setup. That took 544w under load. Now add your extra 100w for all you mentioned and you have 644. A 750 - 800w unit would be more than enough and still give you a little room for additions. you just wouldnt needa 1kw unit.

Keep in mind that their performance setup had two 8800 ultras in it. Its a shame they didnt add info for newer cards..

It's a good article and good find. What he's trying to say is that when you overclock and overvolt the GPU etc, they will consume about more watts, easily 100watts more. Also, when you have lots of hdd and fans, you can have an additional ~50 watts. That is a total of ~150watts, which is, IMO, a significant number.

Is it me or are you sounding very defensive? I'm referring to CGR.

When you overclock and overvolt. It throws out all them figures.

I know my modest machine. Which is overvolted and running a lot of fun things. Will suck up much more than what the myths article will give info for.

What about my four hard drives .. Lights and fan controller? I do have more than just a few fans. Though they are running low voltage. I give all this about a 100 watts leeway by itself. Overkill. But I do not want to go near the top end of what power my machine (better yet PSU) can handle. I got led fans, leds and UV for when I want to make the machine look purdy when company comes over. All the drives I have are function.

Good guide for those who run regular machines

[Enablingwolf]

Is it me or are you sounding very defensive? I'm referring to CGR.

:D I didn't take it as so.

It is sort of true. Most common overclocked systems just plain do not need a kilowatt unit. I also think the common house can't support over 1kW anyways. Unless you put in a higher rated circuit.

For a common setup, that article is good enough. For us experienced overclockers and the folks who understand what a PSU can and can't do. It is not all that informative.

Myself, I have a 600watt unit in case I am forced to bump up the power a little. The main reason I haven't installed it yet. This one suffices, long as I keep it in what it can handle. (The concept behind the article.) The other reason I haven't installed the other unit. I flat out do not like the noise it makes. The tone it has is not to my liking. When this Modstream (TopPower) starts getting loud. I know I am pushing it. Usually it is whisper quiet. This 450 has gone through a few machines now. In an offhand way. I am supporting the concept behind the article, not blindly. I know for a fact, this unit is pushed to an inch of it's soon end of life. I have been saying that for a couple of years now though.
:bday:

[burebista]

For a common setup, that article is good enough. For us experienced overclockers and the folks who understand what a PSU can and can't do. It is not all that informative.
Ditto.:thup:

For 90% of home users with single GPU (X2 included) and dual/quad CPU's a 500-600W PSU is enough.
For 9% of enthusiast gamers with high-end SLI/Crossfire and casual clockers a 850W PSU is enough.
For 1% of enthusiast gamers and hardcore clockers (water, dice, LN2) a >1kW unit is suitable.
Of course I speak here of good brands PSU's.

[Mpegger]

Just a fyi and reference points others could use to compare to thier systems...

At the AC outlet, my main system is using 215 Watt/Hrs when idle.

Figure that the psu I have is around 85% efficient (at its best), that means that the system is really only using around 182 Watts. That's the o/c cpu (with EIST enabled [2.4GHz idle]), and o/c 8800GTX idle, 4 sticks of ram, 3 hard drives, 2 Large fans, 1 water loop (and a partridge in a pear tree...), the sound card, and numerous USB components connected.

When stressed (normal gaming) the reading @ the outlet is about 322 Watt/Hrs.

Again, with a 85% efficiency, your only talking about 273 Watts being used by the system. That's the cpu kicking into its normal speed, and the 8800GTX as well being stressed.

Either value is well below the total my PSU can provide which is 600 Watts.

Did I really need a 600 Watt PSU? Not really. A (good) 400 Watter sould have more then sufficed for my system. In fact, my previous main system (2nd system in my sig) uses just a 400 Watter, and had more hard drives, fans, and various other components installed within it. But as others have pointed out, it is better to have the PSU as least stressed as possible to ensure longevity, as well as head room for any future expansion you may do to the system.

Just another side note, one other aspect of PSUs I would like to point out that the article didn't seem to mention, is that all PSUs are rated for the TOTAL output of all the combined voltages available.

A 600W PSU may be able to provide up to 450W on the +12V rail, and up to 250W on the +5V rail. There is also a -12V rail and a +3V rail, each with thier own rating. Notice though that the two main rails have already exceeded what the PSU says its rated for. The individual rail may be capable of providing up to that amount, but only if the other rails arent being stressed as much either. You'll usually see on the side of the PSU where it list the Wattage available, a row below the ratings stating that the total combines Wattage of those two voltages cannot exceed X amount, and then another row stating that the combined Wattage of all the rails together cannot exceed the amount the PSU is rated for (in this case, the 600W). One could overload a PSU by exceeding the wattage on one of the railings, without actually going over the total combined wattage available, or not leave enough wattage available on the other railings.

This is the one reason why its generally recommended to not use a multi-rail 12V PSU. Your video card may only use 120W max, but if your 12V rail that's hooked up to it can only provide a max of 100W, it doesn't matter that your PSU is "800Watts", as again, that would be the total it can provide across various rails (3V, +5V, -5v, +12V1, +12V2, +12V3, etc etc).

[Enablingwolf]

At the AC outlet, my main system is using 215 Watt/Hrs when idle.



How good is the Killawatt your using? What is the plus or minus? I am not going after you. Just asking a question. Since I never really put all my faith in them. Should I ? I am not being a PSU snob. Just asking...

I am just skeptical of a 12 dollar (reader) part. Hell, even the Fluke has its variances. I still am sorta old school.. Read three... Use one tree.

[dogbert_2001]

I'm skeptical of anyone who says Watt/Hr

[Oklahoma Wolf]

How good is the Killawatt your using? What is the plus or minus? I am not going after you. Just asking a question. Since I never really put all my faith in them. Should I ? I am not being a PSU snob. Just asking...

I am just skeptical of a 12 dollar (reader) part. Hell, even the Fluke has its variances. I still am sorta old school.. Read three... Use one tree.

They're easy to fool at times. I'm running into more and more units for reviewing at jonnyGURU.com that read wrong (low) on those things. I even had a non PFC unit fool it last week, which is rare. The KAW is a nice toy, but that's all I consider it to be.

[Enablingwolf]

They're easy to fool at times. I'm running into more and more units for reviewing at jonnyGURU.com that read wrong (low) on those things. I even had a non PFC unit fool it last week, which is rare. The KAW is a nice toy, but that's all I consider it to be.


It is partially where I am going off of. Seeing that video of the big stuff showing the kill a watt lying made me realize. .. They are fun, but I am not going to buy stock due to the return of the readout.

[Mpegger]

I'm skeptical of anyone who says Watt/Hr

Coming from you with your particular avatar, I find that line extremely hilarious. http://www.jal2s.com/uploader/files/1/crackup.gif

Watt/Hr, Watt-Hr, Watt per Hour = Amount of wattage a device is using in a hour long time period. Simply stating Watts, without first establishing the time period its being measured in, could mean any time period at all (Watts per day, per month, per year, Startup Watts, Peak Wattage, etc). Its just naturally assumed in this day age that Watts automatically means a measurement over an hour.

According to the manual, the Kill-A-Watt, which is in fact the device you all assumed I am using to measure the Watt/Hr, is accurate to within 2%. At 215W, that means the device can be off by as much as 4.3W. I've used my Kill-A-Watt with single "fixed" wattage devices (Light Bulbs, my network switch, fans, etc) and it appears to be as close as it can be for being a mass produced device.

Are there better devices? Of course, but just as one may not trust a $12 device, I'm not about to invest in a $100+ one either just to have a little more peace of mind that my readings are not off by no more then 1%, or to be accepted as true or correct by others. Want more accurate readings from me? I'll give you my address, you buy the device, and mail it to me for my personal usage, you foot the bill of course. :p

[cyberfish]

Watt is a unit for power, the rate of energy flow. It's defined as energy/time, so one watt = one joule per second. The Watt hour (WHr) that we commonly hear about is watt MULTIPLIED BY time, to give the energy consumption per hour.

Unfortunately what you (Mpegger) said is totally incorrect.

[Oklahoma Wolf]

According to the manual, the Kill-A-Watt, which is in fact the device you all assumed I am using to measure the Watt/Hr, is accurate to within 2%.

So... 91% efficiency on this unit is accurate?

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=108

I got those same results with two Kill-a-Watts. One didn't work, so I bought another one and got the same results. They're reasonably accurate to a point when they work right. Emphasis on the word "when." APFC units can and do fool them regularly and often in the lab.

[dogbert_2001]

Watt is a unit for power, the rate of energy flow. It's defined as energy/time, so one watt = one joule per second. The Watt hour (WHr) that we commonly hear about is watt MULTIPLIED BY time, to give the energy consumption per hour.

Unfortunately what you (Mpegger) said is totally incorrect.

This guy speaks for me.