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[Solved] Power Bill for i7 with HD4890?

Forum CPU & Components : Power Supplies, PC Cases & Case Mods - [Solved] Power Bill for i7 with HD4890?

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Best answer from JohnnyLucky.

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andy5174   09-07-2009 at 01:13:16 PM

How many kw-hrs does the i7 build with one HD4890 graphic card consume each month? What percent is it in the total energy consumed each month? How much does it cost?

How much does 30 x 8 x 0.025kW-hrs cost? (Especially peoples who live in Christchurch, New Zealand with Meridian Energy company!)

cheers

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Best answer from JohnnyLucky
I checked the stats for Corsair power supplies over at 80plus.org. That's the site for the Electric Power Research Insitute that measures and certifies psu efficiency. All of the Corsair power supplies reach peak efficiency somewhere around 50% of load. So far so good. Peak efficiency for the models range anywhere from 80% to 90%. That's good too. The efficiency fluctuates but it is quite respectable over a broad operating range of about 25% to 100% load.

What's missing is a list of the rest of your components and some idea of what you plan to do with them. In terms of cost of actual electrical consumption as measured and billed by the electric company, you might want to consider the power draw at the electrical wall outlet (mains). Based on your components and what you do with them, how much electrical power will be drawn at idle, 50% load, and 100% load? How much of the time will you be operating at 50% load? Have you figured that out before looking at power supplies?

The power draw at the wall outlet is different from the power delivered by the power supply to the components. The power draw at the wall is usually higher and is dependent on the system components. The power delivered by the psu to the system components at 50% load varies from model to model. Which model delivers the correct power to the components to achieve peak efificiency at 50% load?

The 4890 video card itself uses about 45 watts at idle and about 125 watts at peak draw.

An Intel core i7 system with the 4890 uses a grand total of about 207 watts at idle and 287 watts at full load. That's the total power draw at the wall outlet.

Which Corsair power supply reaches peak efficiency for a system that draws 287 watts at the wall outlet during full load? The Corsair HX620. It reaches peak efficiency when drawing 364 watts at the wall while delivering 308 watts to the components. In contrast, the Corsair 850 reaches peak efficiency when drawing 475 watts at the wall and delivering 428 watts to the components.

Is it that simple? 364 watts versus 475 watts at the wall outlet? No. There is still the matter of efficiency over a broad operating range. The Corsair HX850 which is a Gold certified psu is more efficient when drawing 308 watts at the wall outlet than the Bronze certified HX620.

So, how much is it going to cost you to run your i7/4890 system, 15 hours a day for an entire year?
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andy5174   09-07-2009 at 01:47:02 PM

Never mind! I figured it out already.

Reply to andy5174
one-shot   09-08-2009 at 08:45:31 AM

.025/KW is pretty cheap. Are you sure you didn't mean 0.25/KW?

Message quoted 1 times
------------------------------ Antec P182, i7 920 3.7Ghz @ 1.3V, Xigmatek 1283, Asus P6T X58, 3 x 2048MB OCZ Plat DDR3 1600 RAM, 2 EVGA GTX260 Core 216 in SLI, WD 160gb,320GB 1TB WD Black. Corsair 750TX. Acer 24" Monitor. Vista x64 Home Premium.
 Reply to one-shot
andy5174   09-08-2009 at 08:57:13 AM

one-shot wrote :

.025/KW is pretty cheap. Are you sure you didn't mean 0.25/KW?


Yes, I meant 0.025kW. It's the approximate amount of energy saved by a Corsair HX750 compared to Corsair HX620. I found that Corsair HX750 is at a better cp rate if you use the pc 15hrs a day for at least 3 years in Christchurch, NZ.

Reply to andy5174
one-shot   09-08-2009 at 08:57:40 PM

With one 4890, both of those PSUs are pretty large. I would use 750W for Xfire, but the 620W will be more than adequate for 1 GPU.

------------------------------ Antec P182, i7 920 3.7Ghz @ 1.3V, Xigmatek 1283, Asus P6T X58, 3 x 2048MB OCZ Plat DDR3 1600 RAM, 2 EVGA GTX260 Core 216 in SLI, WD 160gb,320GB 1TB WD Black. Corsair 750TX. Acer 24" Monitor. Vista x64 Home Premium.
 Reply to one-shot
andy5174   09-09-2009 at 03:11:16 AM

I am considering those two as their efficiency is maximized at 50% load which is very close to the power requirement of my system most of the time. Cheers

Reply to andy5174
Silver CPUs badge JohnnyLucky   09-09-2009 at 05:10:26 AM
Best answer

I checked the stats for Corsair power supplies over at 80plus.org. That's the site for the Electric Power Research Insitute that measures and certifies psu efficiency. All of the Corsair power supplies reach peak efficiency somewhere around 50% of load. So far so good. Peak efficiency for the models range anywhere from 80% to 90%. That's good too. The efficiency fluctuates but it is quite respectable over a broad operating range of about 25% to 100% load.

What's missing is a list of the rest of your components and some idea of what you plan to do with them. In terms of cost of actual electrical consumption as measured and billed by the electric company, you might want to consider the power draw at the electrical wall outlet (mains). Based on your components and what you do with them, how much electrical power will be drawn at idle, 50% load, and 100% load? How much of the time will you be operating at 50% load? Have you figured that out before looking at power supplies?

The power draw at the wall outlet is different from the power delivered by the power supply to the components. The power draw at the wall is usually higher and is dependent on the system components. The power delivered by the psu to the system components at 50% load varies from model to model. Which model delivers the correct power to the components to achieve peak efificiency at 50% load?

The 4890 video card itself uses about 45 watts at idle and about 125 watts at peak draw.

An Intel core i7 system with the 4890 uses a grand total of about 207 watts at idle and 287 watts at full load. That's the total power draw at the wall outlet.

Which Corsair power supply reaches peak efficiency for a system that draws 287 watts at the wall outlet during full load? The Corsair HX620. It reaches peak efficiency when drawing 364 watts at the wall while delivering 308 watts to the components. In contrast, the Corsair 850 reaches peak efficiency when drawing 475 watts at the wall and delivering 428 watts to the components.

Is it that simple? 364 watts versus 475 watts at the wall outlet? No. There is still the matter of efficiency over a broad operating range. The Corsair HX850 which is a Gold certified psu is more efficient when drawing 308 watts at the wall outlet than the Bronze certified HX620.

So, how much is it going to cost you to run your i7/4890 system, 15 hours a day for an entire year?

Reply to JohnnyLucky
andy5174   09-09-2009 at 05:29:28 AM

@JohnnyLucky
WOW! Amazing professional answer.

How did you find out the power consumption for each component and the whole system at idle/full load?

Is the power requirement of i7/HD4890 system you mentioned with i7-920 at stock or 4GHz?

Thank you!

Reply to andy5174
Silver CPUs badge JohnnyLucky   09-09-2009 at 07:18:19 AM

I have a large collection of web pages bookmarked with reference charts that I ran across. Some of them were posted in other threads by veteran posters at this forum. Some of them are from Tom's hardware articles. Some are from other web sites that do technical reviews like jonnyguru.com, hardwaresecrets.com, xbitlabs.com, and others. Google is my best friend when I can't find information at the usual web sites. For example, for the 4890 I searched for 4890 power consumption. Works like a charm.

Here's a link to the power consumption chart in a Tom's Hardware article published last January that I like to quote:

http://www.tomshardware.com/review [...] 122-6.html

Here's a link to a power consumption chart over at the atomic web site that theanimal likes to quote:

http://archive.atomicmpc.com.au/fo [...] c=7&t=9354

The numbers vary. That is normal. A lot depends on the system components, type of testing, and how the measurements were taken. One site might use a stock Intel Core i7 while another site might overclock a system. One site might measure the power draw at the wall outlet while another site might have a device that can actually measure a video card's power draw. Another site might push a system to it's limits during a game. It just depends.

The psu power draw at the wall outlet, delivered power to the components, and peak efficiency stats were from the Electric Power Research Insitute:

http://www.80plus.org/manu/psu/psu [...] =25&type=2

Moderately overclocking an Intel Core i7 doesn't add too much to overall power consumption. Hardcore gaming, extremely serious overclocking, and mutiple high end video cards combined for a suicide mission to save the planet from alien invaders is a completely different matter.

EDIT - BTW, I actually don't get too excited about peak effciency. Instead, I look at efficiency over a broad operating range. Many of the newer high quality power supplies have expanded the range from about 25% to 100% of load. It makes sense since system power requirements will vary depending on the task. We also have to consider people who are a very limited budget.



Message edited by JohnnyLucky on 09-09-2009 at 07:29:13 AM
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