Building a gaming PC

[lumberjim]

[tw]

Originally Posted by glatt

Seems to me you should add up the peak values for all the components, and get something that is equal to that number. Since it's unlikely that you will find a power supply with exactly that number, you should buy the next size up.

Which is what engineers at HP and Dell have done for decades. His 800 watt supply would never see a 400 watt load. Similar computers from those manufacturers only need 200+ watt supplies to power every future part. These numbers are easily calculated since every peripheral connector (ie PCI or video card slot) and other connectors are limited to so many amps. Add all up and lower wattage supplies selected by HP and Dell engineers are more that sufficient.

Getting a layman to add those numbers is virtually impossible for a majority. Simpler to tell him he needs a 600+ watt supply and sell him an 800 watt supply for a computer that never consumes even 300 watts.

Watts is a useless design number. Current (amps) for each DC voltage is relevant. But most computer assemblers (amazingly) cannot add those numbers. Easier is to sell supplies on watts.

Some power supplies are rated at their output power. Others rated for how much is consumed. So a 250 watt power supply from a major manufacturer might also be sold as a 350 watt supply to computer assemblers. Nobody lied. Just another characteristic played with numbers that explains why many are told to buy an 800 watt supply - when a 200+ watt supply is more than sufficient. If he really needed a supply anywhere that large, then his computer can also toast bread.

This game continues. For example, I recently purchased a used power supply to fix a computer. That supply marketed to computer assemblers as ATX was missing essential parts necessary to make it ATX compatible. No problem. Holes for missing parts were occupied by jumpers. Parts removed from a defective supply replaced those jumpers to upgrade the new supply with ATX required functions. Supplies missing essential functions are extremely profitable since so many assume all ATX functions exist only if a computer boots.

Another feature of the game. Legally, only a computer assembler must know and meet industry standards and Federal regulations. If a power supply is missing those functions, then the computer assembler (not power supply manufacturer) is legally responsible. Many ATX power supplies are missing essential features that, for example, mean a power supply failure cannot and will not harm other computer parts. Then naive consumers actually believe a motherboard or disk drive damaged by a failing supply is acceptable. ATX standards define functions that make damage impossible. But some supplies are marketed missing such functions. Especially easy when the supply does not come with that long list of specs.

Step one for selecting any supply is a long list of numeric specs. Irrelevant is even if a consumer does not know what those numbers mean. If that long list of specifications is not provided, then a supply can be and may be missing essential and required ATX functions. And the few who actually know what those numbers mean cannot 'blow the whistle'. Unfortunately, most computer assemblers see a computer boot. That proves all ATX functions exist? No. But most consumers assume otherwise only because it boots.

An industry phrase (forgot the symbol) is now marketed that says a supply meets ATX standards - that is not missing essential functions.

[Undertoad]

Getting a layman to add those numbers is virtually impossible for a majority. Simpler to tell him he needs a 600+ watt supply and sell him an 800 watt supply for a computer that never consumes even 300 watts.

No adding required, just go here, or to any other the other power calculators on the net, googlable with the phrase "pc power supply calculator".

Putting in the chosen components, allowing 3 high-performance fans and 3 USB power drawn devices (conservative in this day of USB charging), and with a 20% figure for capacitor aging, and overclocking a bit, the Thermaltake calculator says 476W is advised. We are giving headroom for additional components/USB charging and for enough amperage on the +12V rails.

Y'ever look at a video card in the last five years tw? They are massive. Take up more space than any other component and have their own dedicated rail. They are often as powerful and have as much memory as the motherboard. That's why it's a gaming rig, the type that HP/Dell generally do not sell.

[tw]

Originally Posted by Undertoad

No adding required, just go here, or to any other the other power calculators on the net, googlable with the phrase "pc power supply calculator".

A perfect example of why computer assemblers need 600+ watt power supplies for a system that only consumes 200+ watts.

We know that IDE disk drives can be powered from a USB port. That means a drive cannot draw more than 2.5 watts maximum. I added one IDE disk drive to the calculator. Not even an IDE interface card. Wattage increased from 88 to 105 watts. Had I added the interface card, it might have added another 14 watts. It says my disk drive consumes 17 watts? A 5400 RPM disk must not even consume 2.5 watt? How can this be if the calculator is so responsible and useful?

A disk drive interface card does not consumer 14 watts. It does not even consume half that.

The calculator also says these are continuously available - not maximum - numbers. So a disk drive that at maximum can only consume 2.5 watts may (according to the calculator) consume more than 17 watts? And its interface also is a toasty 15 watts? Yes. That is what the calculator says. Overly excessive numbers so that the power supply will be grossly more than required.

Thermaltake is selling power supplies to computer assemblers whose eyes glaze over with numbers. Your calculator says a less than 2.5 watt drive consumes more than 17 watts. Another example of why computer assemblers recommend 800 watt supplies for systems that barely consume 200 watts.

But again, wattage is useless for defining power requirements. Current draw for each voltage is relevant. Since consumers and that calculator cannot do that, then all simply provides a wattage numbers that is twice (or six times) more than required.

How many watts does the gaming video card consume? Telling us that the number is big is classic junk science. What exactly are the numbers for video cards in the past five years? As I say often and bluntly, useless claims have no numbers. Informed claims also provide perspective. How much current for each voltage was and is now required for video cards?

Demonstrated by the power supply is why so many recommendations for computers are often uninformed. How to separate the useful recommendations from hearsay: subjective and bogus claims provide no numbers. Or hype numbers from hearsay without any reasons to believe those numbers. Due to so much knowledge from hearsay, the same computer using a 200+ supply provided by engineers is also found with an 800 watt supply recommended by computer assemblers informed by a Thermaltake calculator. A majority will recommend an 800 watt supply. And other unnecessary components.

[glatt]

How many watts does the gaming video card consume? Telling us that the number is big is classic junk science. What exactly are the numbers for video cards in the past five years. Wild speculation and junk science says it is large - a useless claim because it is subjective. Honesty demands that claim include a number.

I thought we covered this.

http://www.asus.com/Graphics_Cards/G...specifications

"Power Consumption:
up to 225W2 additional 6 pin PCIe power required"

If you don't trust the manufacturer, then how are you going to get that number? Pay for the thing and then test it? Ain't nobody got time for that.

[tw]

Originally Posted by glatt

I thought we covered this.
"Power Consumption:
up to 225W2 additional 6 pin PCIe power required"

That is not the power it consumes. That is an inflated number that customers are told. If the spec was written for a designer, it lists amperes for each voltage. Why is nobody's computer toasting bread? That question alone demonstrates wide variation between what is actually needed verses what a majority recommend.

The card may consume just over 100 watts. So we tell the computer assembler to provide a supply with an additional 225 watts. An example of why reality and what most computer assemblers recommend often varies significantly for other computer parts. We can also discuss another popular myth associated with Arctic Silver.

[lumberjim]

Is there any reason NOT to go with a power supply that provides more than what's strictly needed? I chose the 800 on the recco of the guy at Tiger Direct. I had a power supply fail in a Dell computer once, and did not want a repeat of that experience. I may very well upgrade my rig in future. The price difference was not prohibitive as I recall. Why are we spending so much time on this? Just tw wanking about how stupid everyone else in the world is, as usual? Thought so.

[glatt]

Originally Posted by tw

That is not the power it consumes. That is an inflated number that customers are told.

So how, specifically, do you find the real number?

[tw]

Originally Posted by glatt

If you don't trust the manufacturer, then how are you going to get that number? Pay for the thing and then test it? Ain't nobody got time for that.

Nobody said the manufacturer is lying. He has simply added a safety margin due to who his market is.

One can easily learn what the numbers really are by measuring. So many did that to learn their computers mostly consume around 100 watts. Most computers rarely exceed 200 watts in full load operation. One actually got his gaming computer to consume 400 watts.
What is your desktop power usage while browsing these forums?

41 watts idle - 109 watts running Prime95

Someone blamed the measuring device because numbers did not agree with popular hearsay:
I have proved Kill-A-Watt accuracy .. NOT GOOD.

at idle I was sitting at 65W and it peaked at 102W booting up.

These people obtained real world numbers. And that is the point. They got facts. Whereas most who recommend computer parts only recite popular hearsay. Always take what the majority recommend with a grain of salt. Especially when claims are subjective - not tempered by numbers. Demonstrated by the PSU is why so many myths are so often believed - ie Airborne cures the common cold or Geritol for a longer life.

If that video controller spec is useful, then it cited current (amperes) for each volt. Computer assemblers are told to get a power supply at least twice as large as necessary. A 200 watt computer needs a 400 watt supply. To avoid clogging help lines. Thermaltake may then recommend a 600 watt supply. Then consumers know they need 800 watts.

[tw]

Originally Posted by lumberjim

I chose the 800 on the recco of the guy at Tiger Direct. I had a power supply fail in a Dell computer once, and did not want a repeat of that experience.

That is also another popular myth. More watts means a more reliable power supply. Not true. In fact many power supplies have less stress when operating at closer to 100% power. Some technology supplies are at greatest stress when at 50% rated power.

But hearsay (and no numbers) easily convinces many that more watts mean better reliability.

[Undertoad]

If you don't like Thermaltake, try any of the 30 other power calculators.

[glatt]

Originally Posted by Undertoad

It's the video card that consumes all the power. They are mighty beasts these days...

I just saw Philthy's picture of the beast on Facebook. You are absolutely right.

[Undertoad]

Of course, and did you ever see one of those in an HP/Dell configuration? You can't even get one of those into the flipping case!

[tw]

Originally Posted by glatt

I just saw Philthy's picture of the beast on Facebook.

Good. You have numbers. What are they?

[Undertoad]

The EVGA GeForce GTX 660 has a minimum requirement of 24 amps on its own 12V+ rail.


watts = amps x volts OR P=IE as I learned it