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POWER SUPPLY KNOWLEDGE BASE important things that a builder should know

#1 User is offline   chuck4456 

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Posted 03 October 2007 - 09:23 PM

Here at TRP we overclock and benchmark. We strive to assemble the fastest and most powerful desktop PCs on the planet. Naturally our systems require the power supplies with the greatest intestinal fortitude. There are many systems out there that may not require such strategic firepower.
What is the best power supply for your system?

THE STORY OF PACO RODAN

Paco Rodan (pronounced HRO-DON) needs a new power supply.
He has a system with an ASUS P5KPL motherboard and an E6300. The motherboard has onboard graphics but he had a video card installed anyway. It's an old Sapphire X1600 PRO with no power connector. He has two sticks of memory and is using one hard drive with XP. It's a basic system and he is using an old 17" DELL flat panel for visuals. Paco doesn't even know what overclocking is. He thinks that it is something to do with Daylight Savings Time.
So he happens upon TRP one night and CHUCK4456 is lurking in the bowels of the forum.
Paco asks which power supply should he buy.
On nothing but sheer instinct and reflex, CHUCK4456 posts back: "HIGH AMP SINGLE RAIL - PC POWER & COOLING or CORSAIR!" not even bothering to look at Paco Rodan's system specs.
Closer examination of Paco's system specs reveal that one of those units would actually be PSU OVERKILL.
It's unlikely that (even under a full load) Paco Rodan's system would ever even pull as much as 20A total.
Paco doesn't need a mega amp single rail power supply. All he needs is a quality unit. It can be a single rail or a multi rail. In the case of a multi rail, as long as the unit has rails rated 18-20A then he should have no issues powering up and running his PC.
This is where the long standing SINGLE RAIL VS MULTI RAIL argument comes into play.
Both have their advantages and disadvantages. Both have their place in the PC building universe.
Some interesting things come to mind.
Multi rail power supplies actually provide cleaner power because there is less active load per rail. Unfortunately that available power per rail will be limited by Over Current Protection if it is a true multi rail and a quality unit.
Multi rail power supplies cost more to manufacture.
That's where they get you.
It is unlikely that a cheap, sub-quality "ECONO POWER" PSU that is listed as a multi rail power supply actually is. They are normally low cost, low quality single rail units with low amperage capabilities an no OCP.
That's when hardware starts getting burned up.
9 times out of 10 the power supply just blows, but there is always that 10th time in which a motherboard or video card is lost.
As has already been mentioned, most mid-range or home unit PCs will never even come close to producing loads that will shut down the power supply or create a malfunction, so a top quality multi rail PSU will be all that those units will ever need.
A builder needs to be aware when he is crossing the line between a mid range and a high powered system.
Rail specifications are vague as to which connector is connected to which rail and usually not available at all.
A single rail power supply has one output circuit that pumps 12V to all of the connectors. 12V rails are not current limited and all available amps are also available at each connector.
If you are purchasing a video card that has a power connector, then your safest bet is to choose a high amp single rail power supply. If you are installing multiple GPUs or it's an OVERCLOCKER (or both) then it's a no brainer.
High amp single rail power supply all the way.

WHAT IS A SINGLE RAIL POWER SUPPLY ???


POWER SUPPLY WATTAGE AND AMP CALCULATORS

Most of us are not able to spout off the exact power demands of a piece of PC hardware. That is why we are supplied with calculators that feature formulas to assist us. Although none will be exact, most of the current power supply requirement calculators will get you in the ball park and close to home plate if you follow the guidelines and have a good system build plan.
Keep in mind that it's not all about required wattage. Wattage is but a portion of the formula. A builder must consider the load requirements of the system hardware and therefore he will need to determine the necessary Amps as well. As you have already read, a builder can have 1000W available but if his PSU is going to shut down when it reaches a 20A threshold then the unit is nothing but useless junk.

Here are several of the more popular PSU requirement calculators.
Of course after you have completed all of this, if there are still questions in your mind as to which unit you will need, start a thread and ASK!

Here's a new one from CPU-Z.

PSU WATTS & 12V CALCULATOR

It goes into some fine-tuning details.

And of course there is always the "old reliable"...

EXTREME POWER SUPPLY CALCULATOR LITE

Everybody knows about that one.

Here is a quick WATTS to AMPS - AMPS TO WATTS CALCULATOR

WATTS TO AMPS CALCULATOR

Or just remember (ex.) 480W/12V = 40A or 40A(12V)=480W

Unfortunately there is a CATCH 22 when using that formula to determine WATTS to AMPS or AMPS to WATTS when it comes to a multi rail power supply.
Here's why.

Many builders have been misled into the belief that all of the rails can be combined for a grand total of available watts and amps.
Not the case.
If a 480W power supply has 4 rails rated at 20A each and they are added together then there will be a total of 80A.
Using the formula 80Ax12V=960W.
The rails do not combine.
The power supply is capable of of delivering 480W with a 20A limitation. As long as the load demand does not exceed 20A on any given rail, there will be 480W available.

The next thing to consider is connectors.
Does the power supply offer enough connectors to power all of the system hardware?
Are there enough connectors to allow for future hardware add-ons?
Are the cables sleeved?
Are they long enough for suitable cable management?

WHO MADE MY POWER SUPPLY?

You hear it all of the time: "OOOH! That power supply is no good, it's made by GUCHI RAY TECH!" or "Great PSU - made by SEASONIC!"
If I had a dollar for every time I saw that "MADE BY SEASONIC" statement I would be laid up with a babe over in IBIZA or somewhere and I would not be sitting here preparing all of this.
SEASONIC has one of the largest product assembly lines in the world. They assemble a lot of power supplies for many many PSU companies. It does not mean that your power supply is a SEASONIC just because it was assembled by them.
Now there are a lot of rebranded units - ESPECIALLY rebranded sub quality units out there, so if you are buying a brand that no one has heard of or a brand that you have been told NOT to buy, then it might be a good idea to see who's PSU it really is.

UL CERTIFICATION DIRECTORY

This is the UL ONLINE CERTIFICATION DIRECTORY.
I tested it out with some of the power supplies that I had available at the time.

CORSAIR was CORSAIR
PC POWER & COOLING was PC POWER & COOLING
OCZ was OCZ Technology
ROSEWILL was SOLYTECH (WHO???)
XCLIO was CWT


Those were all that I had handy.
___

Here's a good article that was written by OKLAHOMA WOLF from OVERCLOCKERS FORUMS. He is one of the leading authorities on power supplies in the PC building world.

BARGAIN BASEMENT POWER SUPPLIES

After you read that, if you still want to cut corners on your power supply purchase, be my guest!
___

Here's some good videos.

RODNEY REYNOLDS VIDEOS
___

Here's our ol' PC POWER & COOLING standby.

POWER SUPPLY MYTHS EXPOSED

and one of the original SILENCER 610 reports.

PC POWER & COOLING SILENCER 610

Great boxes - too bad they don't pack them in those anymore.

___

This will come in handy for system builders that will be using nVidia graphics.

SLI ZONE - nVIDIA CERTIFIED POWER SUPPLIES

And for all of you ATI builders...

ATI SINGLE CARD CERTIFIED POWER SUPPLIES

ATI CROSSFIRE CERTIFIED POWER SUPPLIES

Here's the INTEL Tested PSU list.

INTEL TESTED POWER SUPPLY LIST


POPULAR REPUTABLE UNITS

There are a lot of good power supply units out there. It all depends on your hardware needs.
Many of the builders here at TRP use PC POWER & COOLING & CORSAIR power supplies.
We are waiting for HOKIEALMUMNUS to complete his power supply testing station and begin his reviews of current power supplies that he will be testing.
At that time we will begin our official list of reputable units.
If you really need to see a list, then just about every other PC Forum will have theirs available.*



UPDATED 7-25-09

*although some of those lists, and units on those lists are very questionable.
Posted Image Posted Image Posted Image
GIGABYTE P55 UD4P-i5 750-Thermalright HR01 Plus-GeIL Ultra-Sapphire HD3870 Xfire-Seagate Drives-Antec 300-22" BenQ-W7
abit IP35 PRO-E8600-Thermalright HR01 Plus-KHX-Sapphire HD4870T-Seagate Drives-Antec 300 w UGuru Panel-22" LG-XP Pro
ASUS P5Q Deluxe-Q6700-TRUE BE-Noctua Fan-Corsair Dominator-Sapphire HD4870 2GB-WD Black Drives-CM690-40" Bravia V-W7
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