# Getting the right Power Supply



## gxsaurav (Sep 3, 2005)

These days, when people buy a powerful new computer system, weather based on athlon64 or Intel Pentium 4, or Celeron D or Sempron, weather they buy a 6600GT or 6800GT, they forget about the most important & vital component of the system, The SMPS.

SMPS stand for Switch Mode Power Supply, one myth people have that with a high power SMPS, in wattage, they will get high electricity bill, but itâ€™s wrong, even if u have a 800W SMPS, if u use only 300W, then the rest of the 500W is simply working idle & wonâ€™t add up to the electricity bill.

Usually people go with the SMPS bundled with the cabinets they choose, cos the price is included in it, now in many cases, this bundled SMPS is enough for the tasks, but in few cases itâ€™s not, because of which is advised to go for a discreet Power supply. Also with the ATX 2.03 specification, Intel & AMD require a 24-pin power supply, & PCI-E based cards also needs extra power

To calculate how much power supply U need, I strongly recommend that you visit here,which can give u a pretty solid rough measurement of your power needs, for your components

Now, U know your power needs, itâ€™s time to calculate how much actual wattage your SMPS will provide, the best way to do is to check it by an electrician, but u can calculate it on your own too

All the SMPS, weather bundled or not, come with a power supply measurement label applied to them, basically itâ€™s like this

+12v = xx A
+3.3v = xx A
+5v = xx A etc

We use simply the equation

Power (W) = Volt X Ampere

Now calculate, it, & U will get the exact measurement about how much wattage your SMPS can actually provide. But, since there is always some loss due to heat, decrees 5% of the total wattage of the SMPS from the total wattage

Suppose U have a 400W power supply, which gives about 350W power when calculated by the above formula, and then simply subtract 18W from it, as heat loss. This new value is the actual power of your SMPS

Right now, in India, exotic power supply brands like Antec or Enemax are hard to find & if found they are costly, a lot costly. U can go for a few good alternatives, like VIP, Powersafe, and a fairly new-comer here these days Colorsit, I gave a Colorsit SMPS to a friend a few days, ago , the Model number is M-330U, which as calculated by the label gives 425W power, so itâ€™s about 410W approx. which is shockingly good.

They also have a Silent Power 12 CM version which has a 12 cm, fan just above the CPU, blowing air outside, & indeed it is silent, the ceiling fan makes more noise. The other options are Standard Model & a Dual fan model, U can check them here

For a thumb rule, I m providing an estimate calculated power for system having

Celeron D & Sempron = 260W
Athlon64 = 340W
Pentium 4 LGA775 = 350W


Keep in mind that with this system I m adding the other components power too, which included, I combo drive, 1 HD, 2 Ram modules, no monitor, 1 GFX card, (6600 level), 2 case fans, usage may very depending on various other components used.


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## Keith Sebastian (Sep 3, 2005)

Nice work. Deserves a sticky.

-Keith


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## gxsaurav (Sep 3, 2005)

thanx, if only the mods can make this & the AMD Cool & Quite thread a sticky, it will help a lot of peoples


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## Yamaraj (Sep 3, 2005)

And then, there are other important factors like efficiency, PFC, dual +12V
rails and total Ampere rating on +12V. It's true that even a fairly powerful
machine by modern standards will never draw 500W of continuous power,
SLI being an exception case. However, many tend to ignore or forget that
no SMPS comes with a 100% efficiency rating. Established branded PSUs
have efficiency rated from 75% to 85% at most. On the other hand, less
reliable ones of the like sold in our country may not even reach 60% of
their rated output in Watts.

So, if any given configuration needs 300W of continuous power, it's better
to go for an SMPS with at least (300/0.75 = 400W) of power, in case of
branded ones like Antec, Cooler Master etc, and (300/0.6 = 500W) rated
from those of PowerSafe and Zebronics made.

Active PFC is available in quite a few power supplies. Antec have them in
their NeoPower and Phantom models. Cooler Master Real Power 450 and
550W come with Active-PFC too. This Power Factor Correction is required
in EU, and helps in saving overall power consumption by the electronic
equipment.

Dual +12V rails are part of the new ATX 2.0 specification, as is the 24-pin
ATX main power connector. The provision of dual +12V rails is made to
split the power load of the Processor, the graphics unit and others to two
or more different +12V rails. This ensures more reliable operation of the
power supply in case of extra power demanded by some other component
of the machine.

Most ATX 2.0 complaint PSUs come with two or more +12V rails, with Amp
rating of 18 each, in most cases. The ATX specification asks vendors to
split the rails when one is sufficient for 18A of power. However, some PSU
makers don't 'exactly' follow the standard. Some vendors have even split
the +12V rails into two, rated 12A and 8A respectively.

Given today's power requirements, it's best to go for a reputed and well
known PSU brand. After all, a well built machine is of no use if it can't be
delivered the power it needs. For a well loaded Pentium4 or AMD Athlon64
machine, one needs a 450W PSU from Antec/Cooler Master with +12V
rated 25A on single rail or 30A on two split rails.

Recommended: Antec NeoPower, SmartPower 2.0, TruePower 2.0, Cooler
Master RS-450-ACLY, RS-550-ACLY

- Yamaraj


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## mohit (Sep 3, 2005)

good useful thread , gr8 stuff gxsaurv and yamaraj. my vote also goes to make this one a sticky.


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## rockthegod (Sep 3, 2005)

real useful stuff gxsaurav.... many ppl who r confused about the ins and outs of the SMPS PSU will learn and make better decisions while assembling their systems... from your simple and well laid out article.


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## gxsaurav (Sep 3, 2005)

in that case, yamraj, I will suggest U take a look at the 400U model found on colorsit website, & check the amperes ratings given there, this model is available for 1k here, let us know here, is that a good SMPS, with good enough power on each rail


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## KHUBBU (Sep 3, 2005)

Nice ,good and informative post. I wud have repped u both if the option was available on this forum.

My vote for making this sticky.


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## Yamaraj (Sep 3, 2005)

gxsaurav said:
			
		

> in that case, yamraj, I will suggest U take a look at the 400U model found on colorsit website, & check the amperes ratings given there, this model is available for 1k here, let us know here, is that a good SMPS, with good enough power on each rail



Honestly, I wouldn't recommend this PSU to anyone with a fairly powerful
Pentium4/Athlon64 machine and 6800/7800 PCI-X video card.

This PSU, the Colors-IT Golden Silent 400 model has a single +12V rail
with only 16A in total. While this rating is not sufficient to power high-end
systems, it can well be utilized in average configurations with graphics
cards of power rating 75W or lower. If this PSU has 75% efficiency, which
I highly doubt, it should be able to supply 280W of continuous power.
An important point to note is that power rating of the power supply drops
sharply with an increase in its working temperature. Most power supplies
come power rated at 25C, and drop in efficiency may reach as much as
5 to 10W per C.

To play safe, one should opt for power supplies with no less than 18A on
+12V in total, even for average system configurations. 

- Yamaraj


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## gxsaurav (Sep 3, 2005)

hmm, u better check this out, taken from colorsit website for the 400U Model

+12V = 25A
+5v = 35A
+3.3V = 28A
-12V = .8A
-5v = .5A
+5V SB = 2.5A

a total of 592W, & even if we assume that it is 75% efficient it gives a power out put of true 445W, isn't that enough for a non SLI system

I m not saying that Colorsit is best, i m simply saying that colorsit is a really good alternative to Antec, VIP or Powersafe if they are not available


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## Yamaraj (Sep 4, 2005)

gxsaurav said:
			
		

> hmm, u better check this out, taken from colorsit website for the 400U Model
> 
> +12V = 25A
> +5v = 35A
> ...



How exactly did you calculate?
It's a 400W model, hence the name 400U. Total wattage can be calculated:

+12V * 16A = 192W
+5V * 25A = 125W
+3.3V * 25A = 82.5W

A total of (192+125+82.5)= 399.5W or 400W.

- Yamaraj


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## zombie (Sep 4, 2005)

*Thank you guys. I already feel enlightened.*


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## gxsaurav (Sep 4, 2005)

go check that page, silent power 12 cm

that the specs for that, we are getting confused, u r taking a different power supply in account, I m talking about M400U Model which is rated at 600W by the company, likewise the M330U is stated as 450W by the company

don't go for power with model numbar, they are different


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## Yamaraj (Sep 4, 2005)

gxsaurav said:
			
		

> go check that page, silent power 12 cm
> 
> that the specs for that, we are getting confused, u r taking a different power supply in account, I m talking about M400U Model which is rated at 600W by the compony, likewise the M330U is stated as 450W by the compony
> 
> don't go for power with model numbar, they are different



Link please?
All I can see is 400W max PSUs: *www.colors-it.com/powers.php

- Yamaraj


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## gxsaurav (Sep 4, 2005)

the link u gave is not for indian version product site

open by the link given above in my post


*www.colors-it.com.cn/03_products/index.asp

these are the products i m saying which are available in here


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## Yamaraj (Sep 4, 2005)

Ah! Why do they have two different sites with conflicting info? Grr!   
Saurav, thanks for the new link. This site definitely has listed some better
power supplies from Colors-IT.

The specs of the Silent Power 12CM Fan are:

+12V * 25A = 300W
+5V * 35A = 175W
+3.3V * 28A = 92.4W

A total of (300+175+92.5)= 567.5W, which is pretty good even for SLI
systems. 25A on +12V is more than sufficient for most systems, but it
may not be enough for very high-end configurations like FXs or dual
cores with 7800GTXs in SLI etc.

Still, this is a powerful power supply for sure, and if it's available at a price
lower than those of Antec SmartPower series, it's a steal.

Do you own a piece, Saurav? What are its full specifications? How many
and which connectors does it come with? Do a full review man!   

- Yamaraj


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## gxsaurav (Sep 4, 2005)

i myself have a Antec truepower 430W, which i baught 2.5 years ago

however, I have given 2 colorsit SMPS to a few friends in their PC

1st one is M300U-PNU Satnderd, with one exhaust fan 80mm

2nd one is M330U-PNE, 12cm Silent Fan, one 12 cm silent fan below the SMPS, above the CPU

the M400U-PNE, costs Rs 1150 here, but with some negotiation it can be baught for less, it is dam heavy I must say, as an estimate by my own, i say it's about 900 to 1 Kg, although it's just my biceps, weight could be less   

All of them come with 24-pin connector for motherboard, with a 24 to 20 pin convertor, 1 SATA Power connector, 4 molex connectors which are splitted in 2 connectors each rail, one standerd 4 pin 12v connector, & the M400U also comes with a 6 Pin PCI-E gfx card connector

true to the name Colorsit, the Power supplies comes in different colors, like blue & red

Colorsit also makes LED Fans & Tubes, since today is sunday, I will enquire tomorrow in the market weather I can get a light tube, U know, this will "spark" things Up

I recomend anyone to go for atleast the Colorsit M350U Silent Power 12 cm model, not only it's silent, it gives

+12v = 20A
+5V = 30A
+3.3V = 20A
etc adding the -12v rails too gives about 480W claimed, at 75% efficiency that about 370W, True power.

anyone wants pics of the side of the PSU for easy finding


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## zombie (Sep 4, 2005)

*This is a quote I picked up from www.slizone.com . Its under the aegis of Nvidia and deals with issues related to SLi. *



> Because you have 3 very important components (your CPU and two GPUs) drawing power from the 12V line, this line is critical. Looking at the specs of the 500W power supply you purchased, there is only one +12V line, giving you a total of only 15A.
> 
> For your SLI system, you should have a power supply that can supply 30A (twice as much!) from the 12V lines.



*The dude has AMD Athlon 64 FX55 // DFI LANPARTY nF4 SLI-DR // 2 BFG 7800 GTXs. So he was advised to get an SMPS that can supply 30A from +12V lines. Do we have any SMPS able to meet that criteria ???*


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## gxsaurav (Sep 4, 2005)

u can look for antec truepower 2.0 450w


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## gxsaurav (Sep 4, 2005)

u can look for antec truepower 2.0 450w


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## Yamaraj (Sep 4, 2005)

zombie said:
			
		

> *This is a quote I picked up from www.slizone.com . Its under the aegis of Nvidia and deals with issues related to SLi. *
> 
> 
> 
> ...



nVIDIA certified SLI power supplies from Antec are: TruePower 2.0 550W,
TrueControl 2.0 550W and TruePower 2.0 550W EPS. It's not wise to use
a 450W or even a 500W power supply in any SLI setup. In fact, total amps
on +12V matter more than the total wattage of any PSU.

See: *www.silentpcreview.com/Sections+index-req-printpage-artid-265.html

- Yamaraj


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## mohit (Sep 25, 2005)

For a SLI rig i strongly recommend the Coolermaster Real Power 550W SLI (RS-550-ACLY.). It has three +12V lines delivering 30A. check the specs here,

*www.coolermaster.com/index.php?LT=...other_title=+RS-550-ACLY.+Real Power 550W SLI


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## Yamaraj (Sep 25, 2005)

Now that Antec TruePower 2.0 550W EPS (TP2550EPS)
model is available in India, I wouldn't recommend
the CoolerMaster one. Antec is surely the better of
the two and also has great warranty and support.

All Antec TruePower 2.0 550W models - 550W, 550W
EPS and 550W TrueControl 2.0, are nVIDIA SLI
certified, while the RS-550-ACLY isn't. Also, Antec
550W models offer a total of 38A on +12V lines.

I definitely recommend Antec TP2 550W. The EPS
model is a little expensive (~8000), but it's compatible
with both desktop and server systems, and also is
SLI certified.

- Yamaraj


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## supersaiyan (Sep 26, 2005)

pls make this thread sticky mods.


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## Ringwraith (Sep 26, 2005)

*bump* for sticky ...extremely useful thread


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## mohit (Sep 26, 2005)

@ yamaraj
 check this link ,
*www.antecindia.com/spec/true550EPS12V_spe.html

here it shows that the Antec True550 EPS12V PSU gives a max output of 36A on +12V. And note that this is taken during the max load. now when u see coolermaster here,

*www.coolermaster.com/index.php?LT=...other_title=+RS-550-ACLY.+Real Power 550W SLI

this model of theirs i.e Coolermaster Real Power 550W SLI (RS-550-ACLY) gives a total output of 48A on three +12v lines. But these people dont calculate the output at max load and instead they do it at continuity where it gives a total output of 30A on the same three +12v lines. 

doesnt this mean coolermaster is better here ? do correct me if i am wrong.


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## Yamaraj (Sep 26, 2005)

@mohit 

Forget the AntecIndia site, for it gets updated every once a decade! Check this link:
*www.antec.com/us/productDetails.php?ProdID=22551

All TP2.0 550W models, including the EPS one, have 2 +12V rails with 19A each.
This sums up to 39A in total. The model shown on AntecIndia is actually the older one.

CoolerMaster isn't a very reliable name in the world of power supplies. They make
good cabinets and other cooling solutions. When I first set out to buy a decent
PSU for myself, RS-550-ACLY was the first one to attract me to it. But then, I
found out that many PSU manufacturers rate their products higher than they are
actually capable of. And unfortunately, Cooler Master is just one of them.
Recently, there was a comprehensive PSU test conducted by THG. The same model,
RS-550-ACLY even failed to run for 24 hours continunously at its rated full load.
I've seen many users complaining that their CM PSUs switch off even at normal loads.

Here's the THG link: *www.tomshardware.com/howto/200507111/stresstest-12.html
What good is a good-looking PSU, if it switches itself off even at normal loads?
Antec passed the test.

I don't mean to discredit CoolerMaster, but IMHO, theirs are not the best in the
industry. Antec has a lot of experience in this arena, and is quite a respectable
PSU maker company.

And besides, CoolerMaster PSUs are always overpriced, at least in India. Last time
I checked with SMC, the 450W was priced at 6500/-. You can get better and more
reliable Antec ones at this price.

- Yamaraj


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## mohit (Sep 26, 2005)

@yamaraj

thanx for the links n details. ill stay away from coolermaster and advise everybody to do the same. btw me on antec smartpower 400w right now  ..  anyways i have another question.

what is the diff between the basic  TP-II 550 (true power 2.0) and the server one TPII-550EPS12V ?? Both are SLI ready and have the same specs. For a normal system such as AMD Athlon 64 / FX / Pentium-4 / Pentium D (Dual core) do i need to buy the server model or will the basic model be sufficient? I will be using SLi though. Please explain. thanx.


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## Yamaraj (Sep 26, 2005)

@mohit

Antec has released three 550W models in the True Power 2.0 category.
Antec TruePower 2.0 550W, 550W EPS and 550W TrueControl.

The plain 550W model is the basic one. It has SLI and shares the same
number of molex and SATA connectors as the other two. The EPS model
is a special one, for it has both 4-pin and 8-pin 12V CPU connectors.
Desktop motherboards require the 4-pin connector on P4/AMD systems.
Server boards with 2 or more processors, need the 8-pin conncetor.
More important is the SSI standard that the EPS model supports. So it
can be used in both desktops and servers/workstations. It should be
taken as little more reliable than other two models.

The TP2.0 550W TrueControl is a very special (and the most expensive?)
power supply. It supports manual tweaking of the voltages on different
rails, via potentiometers. It comes with a panel which is used to change
the voltage levels. Most users do not this type of voltage management.
Also, if the tweakings are not done properly, it can be dangerous for
both the power supply and the computer.

So, if you'll be upgrading in next 2 years or so, you should look forward
to the EPS model. I've seen some Intel Dual Core motherboards with the
8-pin connector. This means even the desktop systems will switch to server
like connectors in next few years. Remember that servers were already using
the 24-pin connectors now required by the new Intel/AMD motherboards.

For a price conscious buyer, a plain TP2.0 550W is more than sufficient.

- Yamaraj


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## mohit (Oct 9, 2005)

hey guyz check out the new Antec NeoHE power Range .. man these psu's are awesome and just look at their  12V ratings , i checked the 550W NeoHE model and its got a total of 54A on three 12V lines .. and u r reading right .. 54 A !!!! also its compatible with EPS12V as well as ATX12V 2.2 .. check it here

@moderators
please consider this thread for a sticky related to buying the right psu.


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