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Power Supply Reference: Consumption, Savings, And More

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a b ) Power supply
January 11, 2012 4:07:16 AM

very informative!
January 11, 2012 4:47:28 AM

Holy cow. Thanks for that Asus PSU link. I now know what's causing my system instability.

AMD Phenom II x4 980BE OC'd
4 x 4GB DDR3-1600 memory
2x NVidia GTX-580 SLI'd
4x SATA HDD's
1x SATA DVDRW
7x FANs (Water cooled system)

Comes to 1150W recommended. I have a Corsair HX-1000 1000W PSU.
Related resources
January 11, 2012 4:57:27 AM

Still running a Thermaltake 750w toughpower here. Been 5/6 years now. Man this PSU has seen some upgrades. lol. I'll probally buy another toughpower/Corsair sometime in the near future.(If this one ever dies. lol)
January 11, 2012 5:41:47 AM

Still using the same Enermax Liberty 500W from 2006 for my new Sandy Bridge upgrade with GTX 560Ti.
The only reason you'd need more than 500W is if you need to power more than one GPU.

Of course, as stated in the article, not all 500W PSUs are equal. The Enermax Liberty was among the best 500W PSUs in its day, and its quality is still exceptional even by today's standards.
It has dual 12V rails with 22A on each with a combined output of 32A total. Most of the dual-rail 500W PSUs sold nowadays max out at 18A per rail.

The Enermax was definitely ahead of its time, and in general, PSUs sold directly by their manufacturer (OEMs such as Enermax, FSP, Kingwin, Seasonic) tend to be of superior quality than those sold by third-party rebranders (Antec, OCZ, Thermaltake, Corsair, etc.).
January 11, 2012 8:22:13 AM

Was wondering about power cycling and thermal shock... The article said that thermal shock from powering on & off can cause deterioration in a system. You suggest S3 (Suspend to Ram), but does this also cause thermal shock to the system when resuming from sleep mode?
January 11, 2012 11:59:54 AM

^ this. was wondering the same thing
a b ) Power supply
January 11, 2012 2:37:24 PM

Great article and thanks, it'll 'hopefully' make my job easier in the Forum and stop the silly arguments I have recommending PSU's. I really wish folks would stop skimping on their PSU's on nice systems.

Another important point that folks have a tendency to forget is 'electrolytic capacitor aging' which over time takes their once 650W and after a year or so reduces it to 520W~500W aka Capacitor Aging.

Great PSU Sizer -> http://www.thermaltake.outervision.com/
Peak:
100% CPU Utilization (TDP)
100% System Load
30%~35% for Capacitor Aging
January 11, 2012 2:40:04 PM

@cumi2k4 and lordvj : We can only assume it does cause a thermal shock, since only the RAM retains power in S3 mode. The other unpowered components thus cool down during stand by mode, like a regular shutdown.

Very informative article by the way!
January 11, 2012 2:40:51 PM

@palladin9479:

Yeah, me too! I had significantly underbudgeted power for fans (9), ODD/HDDs (8) and USB devices (3), and was going nuts trying to figure out why the system was unstable at times. I thought I had a bad MoBo, or HDDs, or GPU, or ??!?!@#$? Now I know.
January 11, 2012 3:04:58 PM

I'm kind of suspect about the ASUS power supply link. It tells me for my old system, I should get a 600W power supply but I ran a 500W on it for years without problem.
a c 105 ) Power supply
January 11, 2012 3:35:58 PM

The statement about third party rebranders depends on who the OEM is. If Seasonic or Delta makes it (e.g. most Antec units), it is going to be a good PSU. Many Corsair and XFX are made by Seasonic too. Channel Well, Sirtec, and some others have some units that aren't so great.

I found the article of some interest (and will revisit the sleep settings on my own system), but some of it was also years out of date. That's probably hard to avoid on a writing project of this magnitude.
January 11, 2012 3:38:43 PM

Good collection of interesting PSU topics. I especially liked the ACPI information. I have several comments and suggestions to change in the article though. I work in the PSU industry and can shed some light on a few issues.

On efficiency, most people leave out the fact that we tend to use air conditioning here in the USA a good part of the year. Here in the mid Atlantic, we tend to use A/C for about ~ 7 months annually. This adds a thermal penalty to any heat that you dump into the office/home air during those months. With most A/C systems, the cost to remove 1W of heat is an additional 0.5W of A/C power (50% overhead). Taking the above numbers and some rounding, I use an overhead rating of 30% total for any heat dumped into my home / office. So take your power loss numbers and multiply by 1.30 to get the total cost impact to your wallet. This also should be done for using CFL and LED lighting. They are not allowed to use A/C cost in their advertising, so the public does not get to see the true possible savings.

There are several types of UPS systems that you should write about. The one you outlined is called a double conversion unit, which is always processing the power to give a clean regulated sine wave output. These are the least efficient and most expensive though. Double conversion is always taking the AC input, making DC, and using a PWM inverter to make regulated AC again for the output. Double conversion efficiencies are typically around 88-90% efficient, so this can impact you total system efficiency and operational costs. A cheaper UPS is the standby type, which allows the raw utility power to go straight to the load with some light duty surge clamping in between. When the input power voltage goes out of bounds, there is a switch over that is usually around 4-8msec which is faster than the PSU hold up time of 20msec. Since normal operation is straight pass through, the usual efficiency is close to 100% (minus the UPS internal power needs and charging). Note though that some UPS systems are crap and can use upwards to 100W just being plugged in.

I did not follow your discussion on the alarm buzzer indicating overcharge, which should never happen in any UPS. Most modern UPS system implement a battery test to make sure that the battery capacity and internal resistance is able to hold up the load. If the battery fails, they set off the buzzer. In almost all UPS systems, a buzzer alarm is critical - something is wrong. Some UPS systems also monitor the ground feed continuity and will alarm if the input feed ground starts to float making the UPS and the load unsafe to touch.

The UPS output waveforms are not all sine wave. Often the double conversion types are sine wave, adding to their cost. The standby UPS systems are usually step wave which is also called quasi-sine which is marketing term for step wave (to confuse the buyer). Most PC loads and monitors work fine with step wave (and are even more efficient on step wave!), although some PFC PSUs have problems. Magnetic loads can have real heartburn with step wave (motors, transformers) due to high losses and non-sinusoid voltage waveform effects.

Ferroresonant transformers are good voltage regulators, but the way they work is very lossy. A good ferro will only run around 90% efficiency. If your load is attached to a ferro, you are adding another power loss in your system. In my opinion, you are better off spend a few more dollars and getting a UPS (which there are ferro types still out there also).

There is no mention of oversizing your PSU also. Many HTPC and SOHO/home server needs are on 24/7 so power usage and efficiency are paramount to the cost of use / ownership. If you install an oversized PSU, you are taking a efficiency hit (for most brands) that increases your energy usage. The 80 Plus standards do not test below 20% load, so the efficiency of most PSU designs drop off quickly below 20% load. I have seen several that are below 50% with 10% loading. A good analogy on oversizing that I have used before is thinking about car engines. You cannot get a V8 car engine to run as efficiently as a 4 cylinder due to the physics (more friction/mass, etc.). That same effect occurs in a PSU. Larger magnetics, power devices, and other overhead lowers the efficiency at low power. proper sizing can save a good bit of money. Just don't get it too small, especially thinking about system start up (HDD spin up, fans, CPU local PSUs ramping up, etc.).

You comment on thermal shock is great, but there are many other factors to consider in reliability. Spinning down any HDD and fan loads reduces bearing wear for those mechanical parts. But keeping the main motherboard PCB powered and some operation continuing also helps with reliability. The minor amount of heat that is generated helps keep the PCB dry (PCB material is hydroscopic!), which one major part of the high voltage area in a PSU failing after a long storage (like right after purchase) causing a DOA. And as others pointed out in the comments, allowing the system to go into a sleep state will also cause a cool down thermal shock. The biggest problem with thermal shock is that it break solder joints and helps break bond wires/connections in ICs. It also speeds up electrolytic cap leaking and shortens the life. Does anyone remember the motherboard cap failure from a few years ago?

The absolute largest cause of computer failures is caused by ESD damage. The data from companies that keep statistics on this unanimously show this as a fact, but the PC enthusiast industry does not work to educate the end users of this well at all. In the electronics industry as a whole, ESD accounts for nearly 55-60% of all failures! This includes component suppliers, etc. So if you want a great topic for a future article, tackle ESD. It is real and it is very costly when ignored. Ever had a PC part that was DOA, i.e., that just "did not work at all" when powered up the first time and would not work at all? Good chance it was ESD.

Thanks for the article.
January 11, 2012 3:52:30 PM

Buy a power meter kill-o-watt comes to mind. Cost 15-20 and will tell you amps, watts, power factor and cycles per second. Best of all it will measure watts over time so you can check how much your system is using in each of it's states. I like to oversize power supplies by 25% unless upgrades are planned.
January 11, 2012 6:48:50 PM

The low ends of the ranges shown are too high. Discrete video cards are available that use less than 10 watts, same for hard drives. Motherboards rarely exceed 25 watts.
My system has an Intel Core I7-870, discrete video card, 2x2G RAM, 2 1Tbyte hard drives, an SSD and a DVD burner. It usually runs at 70 watts and has never exceeded 200 watts driven hard.
January 11, 2012 8:49:08 PM

I thought it was only -5% tolerance for the -/+12v rail. Good data.
January 11, 2012 10:22:22 PM

Would enabling the S3 sleep mode interfere with OC settings and/or performance?
January 12, 2012 12:12:33 PM

palladin9479Holy cow. Thanks for that Asus PSU link. I now know what's causing my system instability.AMD Phenom II x4 980BE OC'd4 x 4GB DDR3-1600 memory2x NVidia GTX-580 SLI'd4x SATA ......


You have a serious bottleneck there bro ;) . Time to upgrade the CPU.
a b ) Power supply
January 12, 2012 10:50:37 PM

palladin9479Holy cow. Thanks for that Asus PSU link. I now know what's causing my system instability.AMD Phenom II x4 980BE OC'd4 x 4GB DDR3-1600 memory2x NVidia GTX-580 SLI'd4x SATA HDD's1x SATA DVDRW7x FANs (Water cooled system)Comes to 1150W recommended. I have a Corsair HX-1000 1000W PSU.


Yeah... that floored me as well, mine is 900 minimum.

1 x AMD Phenom II X6 1055T OC'd
2 x Geforce GTX 550TI
4 x 4GB DDR3
1 x SSD
2 x HD
2 x DVD-RW
5 x CPU fans (double heat sink)

I know now what's causing most of my heat issues is that I'm running an underpowered PSU (Corsair 750). I will definitely make this my next upgrade.

And that thing about putting systems to sleep, I'll do that more often.
January 12, 2012 11:57:10 PM

Remember that ASUS link is calculating the approximate maximum power draw possible on your system. Basically with everything going full blast which doesn't happen too often.

PSU's in general start to get stressed once their over 80% of their rated output. Prolonged stress can cause components to wear out much earlier then before. This is why a PSU may be fine for awhile but then start to have random issues six months or more after installation. I just didn't think I was burning that much juice, but now it seems I am.
January 13, 2012 2:51:28 AM

Just a question, is it worth watercooling a PSU? I know it would boost efficiency and allow it to put out higher watt than specified, but is it worth it?
January 13, 2012 2:55:16 AM

Umm what ... watercooling a PSU would be a very ~bad~ thing.

Unless your an engineer specializing in those things, do not under any circumstances allow water near a PSU, especially in a high powered system that would need WC to begin with. Your home insurance company will thank you.
a b ) Power supply
January 13, 2012 3:39:33 AM

g-unit1111Yeah... that floored me as well, mine is 900 minimum. 1 x AMD Phenom II X6 1055T OC'd2 x Geforce GTX 550TI4 x 4GB DDR31 x SSD2 x HD2 x DVD-RW 5 x CPU fans (double heat sink)I know now what's causing most of my heat issues is that I'm running an underpowered PSU (Corsair 750). I will definitely make this my next upgrade.And that thing about putting systems to sleep, I'll do that more often.

I would not guess you need that much. Your video cards together will have a hard time pulling 300 watts(and spend most gaming time in the 250 range). That leaves you with plenty of power for the system.

Corsair makes(ok, has made for them) very good power supplies.

This while informative, may have some inaccuracies.

@ A Bad Day.
The issue would be to water cool the transformer(its not built with the kind of surface you can mount a block on easy) it self(that thing can be pushes real hard with the right cooling). And leaks SUCK

@ All.
I know that I have trouble pulling much over 300(in fact have not managed it) watts on my system(single 5870 + 2600K @ 4.4 + 4 sticks of ram + 2 hard drives + 1 ssd + 4 120mm fans).
January 15, 2012 4:12:19 PM

why are you recommending sleep mode when ssds are known of failing from that?
a b ) Power supply
January 16, 2012 2:49:32 AM

medbor said:
why are you recommending sleep mode when ssds are known of failing from that?

Why would and SSD fail from sleep, it is no worse then turning off the computer.

Hibernate will push more write cycles, but general sleep does not(it just uses ram).
January 16, 2012 2:58:25 AM

nukemaster said:
Why would and SSD fail from sleep, it is no worse then turning off the computer.

Hibernate will push more write cycles, but general sleep does not(it just uses ram).



SSD's are not HDD's, stop treating them like they are.

A SSD has a small CPU onboard along with firmware that resembles a miniature OS. They have spare DDR RAM to use as a buffer and as scratch memory for that mini OS.

Depending on the model, they will interpret the sleep command as a shut down command and power off. Unfortunately bringing them back from power off there is a chance of a BSOD happening.

I'm using a SAMSUNG 830 256GB, one of the highest rated SSD's for safety and stability. The SAMSUNG instructions specifically state to disable HDD powerdown to prevent data loss and that the drive doesn't need it. It even has a wizard application that will go through and change your power settings to prevent it from trying to shut down the SSD.
January 16, 2012 11:37:54 AM

thank you palladin!
Anonymous
a b ) Power supply
January 16, 2012 4:54:01 PM

Low end estimates provided in the table are WAY off. Taking all of the minimum #s and skiping the descrete graphics produces a power use of 120w. Yet in the real world the HTPC community builds systems with peak utilization well under 70w with 1080p playback in the 25-40w range.
January 16, 2012 9:30:47 PM

motherboards does not minimally consume 50W that more likely peak consumption
January 16, 2012 11:11:13 PM

medbor said:
motherboards does not minimally consume 50W that more likely peak consumption


Take this from someone who made this mistake, ALWAYS budget for peek on all components. Otherwise you'll get random BSOD's and shutdowns. Eventually you'll start to stress your PSU and it'll start providing less power then designed which only make the problem worse.
a b ) Power supply
January 17, 2012 12:18:15 AM

palladin9479 said:
SSD's are not HDD's, stop treating them like they are.

A SSD has a small CPU onboard along with firmware that resembles a miniature OS. They have spare DDR RAM to use as a buffer and as scratch memory for that mini OS.

Depending on the model, they will interpret the sleep command as a shut down command and power off. Unfortunately bringing them back from power off there is a chance of a BSOD happening.

I'm using a SAMSUNG 830 256GB, one of the highest rated SSD's for safety and stability. The SAMSUNG instructions specifically state to disable HDD powerdown to prevent data loss and that the drive doesn't need it. It even has a wizard application that will go through and change your power settings to prevent it from trying to shut down the SSD.

Thank you, I just assumed it would just power down(something I will keep an eye one for sure). I have a cheap Kingston SSD and I put the system to sleep every night. I do not have idle power down on.
January 17, 2012 4:25:57 PM

i really like these kinds of article they really feed knowledge to my brain XO
January 21, 2012 5:17:26 PM

chaz_musicThere is no mention of oversizing your PSU also. Many HTPC and SOHO/home server needs are on 24/7 so power usage and efficiency are paramount to the cost of use / ownership. If you install an oversized PSU, you are taking a efficiency hit (for most brands) that increases your energy usage. The 80 Plus standards do not test below 20% load, so the efficiency of most PSU designs drop off quickly below 20% load. I have seen several that are below 50% with 10% loading. A good analogy on oversizing that I have used before is thinking about car engines. You cannot get a V8 car engine to run as efficiently as a 4 cylinder due to the physics (more friction/mass, etc.). That same effect occurs in a PSU. Larger magnetics, power devices, and other overhead lowers the efficiency at low power. proper sizing can save a good bit of money. Just don't get it too small, especially thinking about system start up (HDD spin up, fans, CPU local PSUs ramping up, etc.).


jonnyGURU has throttled many PSUs from 10-100% range with little loss in efficiency at low loads when compared to full load peformance. Are jonny's tests flawed? Can you please guide us to reviews that showed a 50% drop in efficiency in the low end? Thank you.

January 21, 2012 10:46:56 PM

Very good article!!!Good job guys!!
i never found similar article with so many details!!!
I knew the most of them but i didnt know that placing wrong the CMOS battery can do such a thing!!!
Thank you for the usefull info!
January 30, 2012 4:47:11 PM

"be sure you get the polarity correct; otherwise, you will damage the RTC/NVRAM (CMOS) chip"

Can't they put a diode on the MB to safeguard this? Some of those cheap coin batteries are notorious for reversing polarity by themselves.
a b ) Power supply
February 5, 2012 12:43:02 AM

The diode drops the voltage(but I doubt they NEED 3 volts to keep it going). I have NEVER seen a battery reverse it self.

That said, almost all electronics seem to say damage will happen if you reverse polarity the battery yet most of it does nothing but not run.

I do not even think a 2032 batter can be reversed in most boards with exception to the ones that have the battery sideways(many small boards.)
!