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Energy Efficiency, PSU's, and UPS's...

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August 8, 2006 2:03:14 PM

Ok I live in Florida so it gets hot on a very regular basis. (I know EVERYONE is hot these days, but Florida is ALWAYS hot! LOL) This of course makes my A/C run like crazy and drives up my power bill. (trust me, there is a good PSU & UPS question coming)

So, my current build is using an Aspire ATX-AS520W 520W PSU and it has been GREAT so far
http://www.newegg.com/Product/Product.asp?Item=N82E1681...

I also have a BELKIN Enterprise F6C1100-UNV 1100VA 660W UPS.
http://www.newegg.com/Product/Product.asp?Item=N82E1684...

Now, also connected to this UPS is a ViewSonic G90FB Black 19" CRT Monitor
http://www.newegg.com/Product/Product.asp?Item=N82E1682...

and my Linksys Wireless B router and Motorola Cable modem. (you can check my sig for the other major components of the system) So with all 4 of these things plugged into my UPS (the tower, monitor, router, and cable modem) the UPS says that I am using 33% capacity. It's a 660W UPS so I assume this means I'm pulling approx 220W of power from the UPS. Now I have a few questions... could that actually be right that I'm only pulling 220W with all that hooked up to it? and does the UPS pull 660W all the time from the wall even though the components hooked up are only using 220W? Also even though my PSU is a 520W does this mean then that I'm not always using 520W? This is kind of important b/c I'm trying to both save energy and make sure I'm not starving my system. I'm planning on building a new system pretty soon and I'm looking at the PC Power & Cooling Turbo-Cool 1000W EPS12V SLI, SSI PSU.
http://www.newegg.com/Product/Product.asp?Item=N82E1681...
It's expensive, but I'm told it's the best. So am I going to be pulling more power since it's rated at 1KW? or is that just the max and the system will only pull what it needs? Sorry so long, but THANK YOU for any help!

More about : energy efficiency psu ups

August 8, 2006 3:46:20 PM

First of all, just because your power is rated at something 520w for you, does not mean that you are using it all the time. It's like a car engine, if your max horsepower is 300hp you are not at 300 all the time.

Your psu will only draw what it requires. What you do have to recognize is that psu's are the most efficient at around 70% to 80% of their rated maximum power. So unless you are going to be using 700w to 800w on average then getting a 1kw is going to make you less efficient.

So unless you are getting the E6800 with 2 7950gx2's with tec/water cooling, 5 hdd's, 4 sticks of ddr2 ram, sb platinum, ten 120mm led fans, and OC everything that can be OC'ed, there is no way you will get anywhere near 700w.
a b ) Power supply
August 8, 2006 10:23:48 PM

The efficiency of the PSU depend on the load placed upon it. The typical premium brand PSU has a sweet spot between 70% - 95% where is would be near it's peak efficiency.

I'm gonna guess that your PC will use about 275w under load (max).

PSU #1 will provide 500w of power.
PSU #2 will provide 1000w of power.

Assume they both share the following characteristics:

Load............................Efficiency

01% - 25%.........................40%
26% - 40%.........................55%
40% - 50%.........................65%
51% - 70%.........................75%
71% - 90%.........................85%
91% - 100%.......................80%

As you can see, the efficiency starts out very low if the PSU is not being stressed. As the load increases so does the efficiency up to 90%. At 91% and higher efficiency will start to decrease again.

If you use PSU #1 (500w), the load will be 55%. Based on the theoretical characteristics of PSU #1, it will be 75% efficient. That means while the PC is only drawing 275w from the PSU, the PSU is drawing 367w (275w / 75%) from the AC outlet.

If you use PSU #2 (1000w), the load will only be 27.5%. Based on the above specs this PSU will only be 55% efficient. So while PSU #2 is providing 275w to the PC, it is drawing 500w (275w / 55%) from the AC outlet.

It's always better to get a slightly more powerful PSU than what you currently need for future upgrades, but going PSU overkill will not only cost you more money upfront, but will also increase your electricity bill if the load placed on it is too "lite".
Related resources
August 9, 2006 12:17:40 AM

http://www.extreme.outervision.com/psucalculator.jsp
This site estimates that my system will consume 284watts of power. That's with a 7600GT. I'm assuming that when I get a DX10 video card, my wattage won't exceed 320. I'm looking at the 430watt Antec Trio. I think that 430watt will produce a good ratio now and also when I get the DX10 card. Does that sound right?
August 9, 2006 12:44:05 AM

Thought you might find this ironic a bit but, seeing as how the title of this post is "Energy Efficiency, PSU's, and UPS's..."

That PSU you listed, the APEVIA (ASPIRE) ATX-AS520W-BK ATX 520W, has no PFC, which protects against things like voltage fluctuations and electrical irregularities that can affect the efficiency of your power supply.

There are three types of PFC: active, passive, and non-PFC. Active PFC provides the best protection, while non-PFC provides the worst.
a b ) Power supply
August 9, 2006 1:16:36 AM

Quote:
http://www.extreme.outervision.com/psucalculator.jsp
This site estimates that my system will consume 284watts of power. That's with a 7600GT. I'm assuming that when I get a DX10 video card, my wattage won't exceed 320. I'm looking at the 430watt Antec Trio. I think that 430watt will produce a good ratio now and also when I get the DX10 card. Does that sound right?


It's difficult to say how much power a DX 10 card will require. A report over at Anandtech stated that the next generation GPU will consume between 130w - 300w of power. I'm sure that is for the premium single GPU and even more power hungry double GPU video cards (two GPUs on a single video card like the 7950GX2). The more down to earth mainstream cards shouldn't be that power hungry.

One thing you need to realize about power supplies is that total power is not important. What is important is the amount of amps on the 12v rails. A PSU will have 3.3v and 5v rails, but the 12v rails are the most important because most of the power is drawn from those rails.

You want to buy a good namebrand 400w - 450w PSU that provides at least 26 amps on the 12v1 and 12v2 rails. Each PSU has a sticker on it that will provide this information. Unforturnately, a clear shot of this sticker is not always provided by the e-tailer.

The following is a list of PSU that I would recommend:

Seasonic S12 430 - $100 + $8 shipping

Antec TruePower TPII 430 - $70 + $6 shipping

Antech NeoHE 430 - $70 + $8 shipping

Enermax EG425P-VE 420w - $65 + 7 shipping

FSP Group AX450-PN - $52 + 8 shipping

XClio 450BL 450w - $44 + $9 shipping

The XClio is not a namebrand like the others listed, but I have read hardware reviews (not user reviews) of this and other PSUs that they sell. This is not only an inexpensive PSU, but it is also pretty good. If you are really on a tight budget then get this PSU.

I highly recommend the Seasonic S12 430 it is a premium qaulity PSU that is both quiet and 85% efficient, but the price reflects their reputation and quality.

The Antec NeoHE is also a PSU that I recommend as well. It too is quiet and 85% efficient like the Seasonic S12. And it is less expensive.
August 9, 2006 3:47:54 AM

WOW... awsome post jaguar! Ok so now I've got to somehow figure out what PSU to get for my new build. Are PSU calculator's very reliable? How can I best pick one out that will match my power usage most efficiently? Here are the parts for my new build if someone can help me figure out what will fit my particular build...

Intel E6700 C2D (which I plan to OC to the best of my/its ability)
Zalman CNPS9500 HSF (I may go water cooling in the next 6 months though)
either an Intel 975X or nVidia 590 based mobo
Thermaltake Armor case w/ 2 x 120mm (1 LED) fans & 1 x 90mm fan
Corsair XMS2 2GB (2 x 1GB) DDR2 800 SLI/EPP
WD 74GB 10K 8MB SATA Raptor
WD 250GB 7.2K 16MB SATAII Caviar RE
Lite-On 16x DVD+/-RW
Lite-On 52x/16x Combo drive
NV GeForce 7900 GTX
Creative SB Audigy 2

ANY SUGGESTIONS? Let's not worry too much about price either... but do list prices if you can so I can get an idea.
a b ) Power supply
August 9, 2006 2:57:33 PM

PSU calculators generally tends to overstate how much power a system will use under a theoretical maximum load. But it's better to over estimate than under estimate. It is not possible for every single component to be stressed all at the same time.

When I look at PSU I generally tend to look only at the 12v rails because most of the power is being drawn from those lines. The 3.3v and 5v are still important, but as long as the 12v rails are strong, there is no need to worry about the other rails.

The following is an estimate based on a non-overclocked system:

Component..............................Power (12v rails)

Intel E6700 C2D.................................59w Click here so see actual measurement.
Zalman CNPS9500 HSF........................6w
Premium motherboard........................25w - Motherboards actually draws most of it's power from the 3.3v and 5v rails. 25w is a "buffer".
3 Fans (2 x 120mm, 1 x 90mm)...........15w
RAM......................................................0w - RAM draws power from the 3.3v rail.
WD 74GB 10K 8MB SATA Raptor............40w
WD 250GB 7.2K 16MB...........................25w
Lite-On 16x DVD+/-RW..........................18w
Lite-On 52x/16x Combo drive................18w
NV GeForce 7900 GTX............................84w - Click here for actual measurement.
Creative SB Audigy 2..............................0w - PCI cards draws power from the 3.3v and 5v rails.

Total Power Comsumption (Max Load).......290w

Some of wattages I used are higher than what I really think they are, but its always better to have a little too much than a little too low.

Like I said, Max Load is theoretical. I imagine power consumption during gameplay will be more like 235w because I really doubt you will be burning a DVD and CD while playing, and both hard drives will not be spinning all the time. When a game does access the hard drive to load an area, the game generally pauses, so the CPU and GPU isn't really being stressed during that time.

Based on the 290w of total power consumption, I would look for a PSU that delivers at least 28 amps on the 12v rails which totals 336w (28 amps X 12v). Under the theoretical maximum load, the load on the 12v rails will be 86%. My guess of 235w during typical gaming means the load will be 70%. Also take into consideration any future upgrades, which means you'll want more than just 28 amps on the 12v rails.

While the efficiency sweetspot of a premium PSU is typically 70% - 95% (in my opinion) I would recommend you try to be closer to the lower end rather than the higher end of the range because:

1. I am guesstimating some of the component power consumption (HDD and DVD) based on some actual measurements from research I've done a while ago.

2. You may want to add in additional components like and GPU for SLI, or another Raptor.


The best thing you can do is to buy a good quality PSU that is rated for very high efficiency like the:

Seasonic S12 430 which delivers 348w of power on the 12v rails (29 amps X 12v), and is rated at up to 85% efficient. - $108 Shipped.

Antec NeoHE 430 which deliver 384w of power on the 3 12v rails. Each 12v rail is rated at 16 amps maximum, but combined all three can only deliver 384w of power. This PSU is also rated up to 85% efficient. - $78 Shipped.
August 9, 2006 3:21:52 PM

I'd add another vote for the seasonics, I have yet to find a review in which they don't come highly recommended. The 500 and 600W versions are actually said to have a higher efficiency than the 430 but if you don't need the power you can save some $. I'd personally go for the 500w version but that's just me, I like to futureproof things a bit.

As a little post script SPCR found the 600W version to be 80%+ efficient at draws from 150-300 watts (and 79%+ from there to max draw). They are also Active PFC models which increases power draw very slightly. The reason active pfc models usually rate as more efficient is that this feature is most commonly packed into only higher quality power supplies but as I said above, it (active PFC) doesn't intrinsically increase the efficiency.
August 9, 2006 7:15:48 PM

The Thermaltake TR2 430W PSU says its 65%+ efficient. What does that mean? Is the avg. efficiency around 75 or closer to 65. I'm presuming if the efficiency doens't drop below 65, it must be around 75-80.
This PSU is half the price of the Seasonic S12. The only main difference I can see is that the Seasonic claims 85% max efficiency. That's great but perhaps the TR2 can reach that as well. The only main feature difference seems to be Active-PFC but what good is that if both are similar efficiency? TR2 could have 90% max. efficiency and S12 60%min. efficiency. I don't want to spend one more dollar than I need to!
a b ) Power supply
August 9, 2006 8:30:31 PM

Quote:
The Thermaltake TR2 430W PSU says its 65%+ efficient. What does that mean? Is the avg. efficiency around 75 or closer to 65. I'm presuming if the efficiency doens't drop below 65, it must be around 75-80.
This PSU is half the price of the Seasonic S12. The only main difference I can see is that the Seasonic claims 85% max efficiency. That's great but perhaps the TR2 can reach that as well. The only main feature difference seems to be Active-PFC but what good is that if both are similar efficiency? TR2 could have 90% max. efficiency and S12 60%min. efficiency. I don't want to spend one more dollar than I need to!


The 65%+ is the max efficiency of the PSU. The "+" doesn't mean it will go up to 90%; it means maybe another 1% or 2% at most. Part of the reason why the Seasonic S12 are more expensive than other PSUs is because of quality components, and for their PSU it translates to very efficient PSUs.

The Thermaltake PSU you are looking at is inexpensive for a reason. Most people do not think of quality when it comes to Thermaltake power supplies. The only exception would be their more expensive PSU. I think it's called the ToughPower series, or something like that.

If Seasonic is too much then get the less expensive Antec NeoHE 430w PSU; it's about $30 less expensive. But it is still more expensive then the Thermaltake.

Don't worry about active PFC, it will have no impact on the average consumer. Businesses care about active PFC because they are billed differently by the Utility Company.
August 9, 2006 10:17:54 PM

At 50% load, would the S12 and TR2 be of similar efficiency? It seems the only benefit would be at a higher load since the S12 can reach a higher efficiency where as the TR2 would stay at 65. When the computer is idling, I see no reason why the S12 would be more efficient but perhaps that's wrong.
a b ) Power supply
August 10, 2006 4:54:07 AM

Quote:
At 50% load, would the S12 and TR2 be of similar efficiency? It seems the only benefit would be at a higher load since the S12 can reach a higher efficiency where as the TR2 would stay at 65. When the computer is idling, I see no reason why the S12 would be more efficient but perhaps that's wrong.



The Seasonic S12 430's efficiency does not drop below 78% as can be seen from this SilentPCReview.com review. That is at maximum load. At just 65w of load (15%) the Seasonic S12 430 is 79% efficient. Even at it's lowest efficiency, the Seasonic will blow away the Thermaltake TR2 at it's best. That's the reason why Seasonic PSU are expensive, they use quality components. I don't know what the TR2's efficiency range is, but I can say that the range will not be tight like Seasonic's 78% - 83% efficiency.

If I had to guess I would say that the TR's efficiency range would be from 45% - 65%.

Compared to CPU and GPU reviews, Power Supply reviews are rare. Even rarer are sites that actually tests the efficiency range of a PSU. In fact SilentPCReview is the only one that does it as far as I know.


I paid $105 for my Seasonic S12 500 over a year ago. That was a true bargain for their 500w PSU. The lowest I've seen it since then was $115 on sale. Their PSUs may not be affordable to everyone, but those who can afford to bite the bullet for it will certainly be pleased.
August 10, 2006 7:52:43 PM

THANKS JAGUAR! Excellent info! :D 
August 14, 2006 6:58:18 AM

that range is massive.
seasonic s12 at idle is 80% efficient, while TR2 is only 50%.
the 400watt sp400 is a little bit more $$ and claims its 70% efficient or greater, so i think the TR2 at 50% is a bit low... but anyway.
If the idle is at 200watt, then s12 is consuming 240 watt and the TR2 is consuming 300watt. A 60 watt consumption difference seems pretty massive. infact, 60watts going into whatever from the wall costs $40 a year. that means that the TR2 if only 50% efficient at idle can cost up to $40 a year extra. s12 pays for itself quickly. of course these calculations taken if computer at idle for 365days a year, and that idle is at 200 watt without any of the windows power saving features enabled. efficiency does pay for itself, since 300watt costs $170 a year, and 240 watt costs $130.
August 14, 2006 7:08:08 AM

claimed TR2 efficiency is 65% or greater. wouldn't the range then be from 65-75?
i don't think it really matters using a 1KW PSU or a 500watt PSU in terms of price. if both PSU's are 70% efficient or higher, and we look at cost to idle for 365days a yr, cost would be the exact same, would they not?
again, I don't think any PSU would go under 65% unless they are some no-name crap.
a b ) Power supply
August 14, 2006 2:36:55 PM

Quote:
claimed TR2 efficiency is 65% or greater. wouldn't the range then be from 65-75?
[\quote]

Like I stated before, if a PSU is rated at 65% or greater I wouldn't stretch that up all the way to 75%. In my opinion uit would be 67% or 68% at best. There is no hardware review of the TR2, so it's actual efficiency is unknown.

Quote:

i don't think it really matters using a 1KW PSU or a 500watt PSU in terms of price. if both PSU's are 70% efficient or higher, and we look at cost to idle for 365days a yr, cost would be the exact same, would they not?
again, I don't think any PSU would go under 65% unless they are some no-name crap.


The efficiency depends the load so 200w on a 500w PSU represents a 40% load. On a 1000w PSU, 200w is only a 20% load. Depending on the characteristics of the two PSUs the 500w PSU may be more efficient that the 1000w with only 200w load.

Since manufactures list the peak efficiency of their PSUs you should accept the fact that if 65% is listed, it is bound to dip below that when the PSU is not operating at it's most efficient load.
a b ) Power supply
August 14, 2006 2:44:25 PM

Quote:
A 60 watt consumption difference seems pretty massive. infact, 60watts going into whatever from the wall costs $40 a year. that means that the TR2 if only 50% efficient at idle can cost up to $40 a year extra. s12 pays for itself quickly. of course these calculations taken if computer at idle for 365days a year, and that idle is at 200 watt without any of the windows power saving features enabled. efficiency does pay for itself, since 300watt costs $170 a year, and 240 watt costs $130.


While an efficient PSU can save you money especially if you live in a city like New York where the cost of electricity is $0.19 per kWH. There is another benefit as well; greater efficiency means less electricity is wasted as heat. Therefore the overall PC temperature will be a little cooler, maybe about 2 degrees Celcius. That could help with overclocking. In the case of the Antec NeoHE and Seasonic S12 series, they are also very quiet since the PSU fan does not need to spin very fast to exhaust the hot air.
!