Choosing the Right Power Supply

C

clarkkent57

Guest
First things first. If you've got a poor-quality and/or faulty power supply, nothing else you do will work to solve your problems. Stick to the basics before you go further...The short answer is to buy a hi-powered, brand name supply, like the new ENERMAX line (430 W or higher) or ANTEC True550. Almost nothing else will do with today's computers. In over 30 years of electronic/computer service, I have found that 85% or more of problems were power-related.

If you want to know more, read on...


Choosing The Right Power Supply

If you?re reading this, there?s a good chance that one of my colleagues or I believe that you could be experiencing problems with your power supply, based upon the symptoms you mentioned in your post, and provided you with this link. Relax, you?re not alone. In 30 years of electronic and computer troubleshooting, I?d say that the majority of the electronic, mainframe, mini, and microcomputer problems I?ve diagnosed and repaired were with the basic power the problematic device was receiving. The symptoms often included random reboots, crashing, the BSOD, lockups, etc.

(As the national support technician for few major computer service companies, working US Defense contracts, I was often the person that had to fly in and correct the problem, or ?walk through? the on-site technician as he closely followed my instructions. I achieved success in my career by carefully reading the manuals, knowing where to go for more information that was otherwise unavailable to me, and/or systematically troubleshooting until the problems were discovered and repaired. I never had the option of giving up.)

The most overlooked component when building or upgrading a PC is the power supply unit (PSU). Some people use their old case and PSU when they upgrade. Some use the PSU that came with their new case. Some people even buy a new PSU. And most inexperienced builders all make the same mistake: The PSU that they?re trying to use is simply inadequate for the job.

Suppose you?re upgrading to a new motherboard, CPU, ram, and video card, but still using the old case and PSU. It?s most likely that you?re upgrading in order to build a machine that is more powerful, faster, has a more colorful display, can number-crunch more quickly, play the latest games, etc. These gains in performance all have one thing in common: They require more raw power. However, have you thought about where that power comes from?

Suppose you?re building a new system with a new case and PSU. Has it occurred to you that the company that you bought the case/PSU from might make more money if they skimp on the supply, even if the supply has a large wattage rating? Most bulk power supply manufacturers don?t make good PSU?s. They use older, cheaper technology, and slap on labels that represent the PSU?s peak outputs, and not their continuous output rating. These companies are intentionally misleading you in order to sell you an inferior product. Brands I avoid when building/repairing my friends? and family?s computers: Allied, Q-Tec, Chieftech, and many others.

For those of you who bought a power supply separately, did you know that you?re only supposed to run a power supply continuously at 30-70% (with 50% being optimal) of its continuous rating for maximum efficiency (which means less heat to you)? Most inexperienced builders either buy PSU?s that are matched to their equipment?s continuous power usage, or ones that are even less powerful than they need. Why? Because they?re trying to save money.

I mean, what?s the fun in a power supply? You don?t get any games with it, there?s no more storage, hardly ever any more bells and whistles, etc. A power supply is boring, and it?s supposed to be, because it?s supposed to provide a stable, reliable platform upon which the rest of the equipment can easily access the amount of power it needs, and when it?s needed. In almost EVERY review of powers supplies, the same point is stressed: Better safe than sorry.

But what does safe vs sorry mean? It can mean that you don?t have to waste money on the wrong PSU in the first place, but it can also mean that you don?t have to replace your expensive ram, CPU, video card, etc. NEEDLESSLY, or because your cheap PSU destroyed them. What? A cheap power supply can wreck your computer? YES IT CAN. A cheap power supply can cause thermal damage, not only from the heat it produces, but also the heat it can create in your components as well. RAM is especially sensitive to heat, and there?s RAM in your CPU, your video cards, and, well, your RAM too. A cheap switching power supply, run at its maximum, or peak, continuously can also destroy components by creating RF (Radio Frequency) signals on your power rails, signals which the components on your peripheral devices were not equipped to handle in the first place.

So this begs the question, how does one choose the right power supply? I?ll illustrate this using my own PC as the example. This is my setup that I use for video processing:

K7N2G-ILSR
Athlon 2500+ Barton @ 2125Mhz
AMD Retail Heatsink/Fan
2 - 512MB DDR333 w/Thermaltake Spreaders (slot 1&3)
MSI TV@nywhere Video Capture
ATI Radeon 9600
120GB Maxtor DiamondMax Plus 9 SATA
30GB Quantum IDE
TEAC DV-W50E DVD/CD-R/W
BTC DVD-ROM Drive
Artec CD-R/W


Using this Power Supply Calculator link:

http://www.jscustompcs.com/power_supply/

I plug in all my equipment values, but some of this can be a little tricky. For example, since I often run the CPU like an XP 3000, I choose the 3000 as my processor; it?s the same chip run at the faster rate. I also choose the ATI Radeon video card, and I select the RAM wattage for 2 sticks of DDR. I also choose every card I have, like my video capture card, but I also select the boxes for the separate cards that correspond to the functions that my ILSR provides as well (and that I use), like sound, USB, Firewire, NIC, etc. ?Although I use the onboard SATA controller, I don?t select the SCSI PCI card, because, in truth, I?ve probably made up for it by selecting all the other corresponding devices, including cards that the motherboard replaces. I check the boxes for the fans and drives I use, and I?m done, right?

Not yet.

I just remembered that I plan to upgrade soon, so I go back and change the values to reflect my impending changes. I mean, I want to make sure that I have enough power to begin with so that I don?t have to replace the power supply again, right?

Ok. Done. I look at the bottom and see that it tells me that I need a 468 watt PSU. So a 480 watt supply will do, right? Wrong.

Remember that, for efficiency, long-life, and less heat, you want your actual power consumption to fall between 30-70% of the PSU?s rating, so add 30% (minimum) to the 468, and you get 468 + (468*.30)= 608 Watts! Holy Cow!

However, I?d only need a 608-Watt supply if I was using all the devices at once, and I don?t. But, in truth, with video and audio processing, I often get close when I process, burn, and monitor at the same time. (Hardcore gamers also get close a lot, as they blast the sound and push that video to its limits.) So, let?s take off 10% (maximum) of 608, for a total of 541 Watts.

I need a 550 Watt supply, but not just ANY 550 watt PSU. I need a supply that can give me enough power on the critical 3.3, 5, and 12V rails combined. I also want a supply from a trusted, name-brand manufacturer, so I start hitting the many online reviews. Here are just two from Tom?s Hardware:

http://www6.tomshardware.com/howto/20030609/index.html

http://www6.tomshardware.com/howto/20021021/index.html

Read these in their entirety. I didn?t post them because they?re pretty links.

In the end, I chose Antec, because they?ve got the reputation, the recommendation, and because the Antec True550 has better specs than the rest of the 550 Watt competition. I also bought it from a reputable company I found on Pricegrabber.com, for the lowest price I could find, $95.00 shipped to my door. (In truth, I wanted two mini-redundant supplies, like the hospitals and military use, but they were too expensive.)

The result? Not only are the random reboots, crashing, the BSOD, lockups, etc., gone like magic, but I also now have ?peace of mind? in that whatever might happen to my equipment in the future, I know almost for certain that the PSU is NOT the problem. I also bought an UPS, because the East Coast Blackout proved to me that even the Antec True550 isn?t going to provide me any power for emergency shutdown if it doesn?t get its power from somewhere.

Even if your problem doesn?t lie in the PSU completely, it gives you a GREAT platform for troubleshooting further. If you?re not reasonably certain that the supply is the cause, borrow one, or buy one that you can return once you?ve solved the problem. But, above all else, BUY THE RIGHT SUPPLY before you do anything else! Otherwise, you could be plugging and unplugging components, buying and blowing up expensive memory, and causing even further damage, until you give up or die.

I mean, I assume you built your own system to enjoy ?more bang for your buck,? right? What?s the fun of a random reboot in the middle of Unreal Tournament 2003?

William Hopkins
Former Staff Sergeant, USAF
B.A., B.S., with Honors
The University of California, San Diego
Clarkkent57@hotmail.com

P.S. It should be noted that while Enermax, ThermalTake, Zalman, Fortron, and others make great PSU?s, and I compared and considered them, the Antec still won out overall in my critical evaluation, like it did in so may others? reviews. You?d probably be ok if you went with another reputable manufacturer as listed above, but pick a supply that gives you at least 230 watts on the 3.3 and 5V lines combined, and still meets the 30% criteria as stated above. Remember, if the manufacturers don?t give you maximum combined specs up front, they?re untrustworthy right off the bat. With power supplies, you definitely end up getting what you pay for. Don?t say nobody warned you.

P.P.S. Update! After recent developments, it looks like Enermax is the leader, but only the latest line of PSU's.
 
Hey,

I read your post, thnx so much. I was acatully one of those ppl who didn't really think that power supply was that big of a deal. Like my last computer I just bought a generic one, and that was a mistake.

Well, I'm actaully building a new computer now. The specs are as follows:

CASE: Aero Cool Jetmaster Mid Tower ATX
MOTHERBOARD: Gigabyte GA-K8NF-9 NVIDIA nForce4 4X (Socket 939)
CPU: AMD Athlon 64 3000 (Socket 939)
MEMORY: PC3200 400MHz 1 Gig (2x512 Meg) 184pin DDR SDRam
VIDEO CARD: eVGA e-geForce 6800 GT PCI-E 16x 256 Megs GDDR3
HARD DRIVES: Western Digital 80 Gig HD @ 7200RPM + Maxtor 40 Gig HD @ 7200RPM
OPTICAL DRIVE 1: Creative 52X CD-ROM Drive
OPTICAL DRIVE 2: DVD-RW
OPTICAL DRIVE 3: CD-RW
+ a Floppy Drive

I will be looking to do a lot of high end games on this machine and I am looking for a power supply to suit my needs. So far I am looking at a COOLMAX 450W SWITCHING POWER SUPPLY (model CT-450) vs. the Enermax Whisper 431W Power Supply (model EG465P-VE)

Here are the links to the PSUs

COOLMAX: http://www.newegg.com/Product/Product.asp?Item=N82E16817159002#DetailSpecs
ENERMAX: http://www.exhardware.com/reviews.php?Id=57&Page=1

The thing is that your Enermax power supply is going to cost me a bit more than the Coolmax power supply. However, I am willing to pay the extra cast IF its needed, but ONLY if its needed. So what do you think. Can you give me an opinion as to which power supply is better suited for my needs

Also, if you think that none of these power supplies are good for me and I should go in a whole new directions completely... let me know what power supply you think I should go with instead, thnx
 
Under no surcomstanses could I recomend the Coolmax PSU.
+3.3V@28A,+5V@45A,-5V@0.5A,+12V@18A,-12V@0.8A,+5VSB@3A

The +12V is way to low for that setup. I would also hesitate to recomend that Enermax PSU, it has only 20 amps on the +12V, and thats a bit low. I suggest you find a PSU with 25 amps atleast on the 12V rail. This is wery important for the system stabillity.

BTW...wrong mobo...choose MSI :biggthumbsup:
 
That review must be of the previous version of the 465P-VE (Whisper). I have the 465P-VE (WhisperII) and it has 33A on the +12V rail and a total max output of 460W. See my signature.
 
Frankenputer said:
That review must be of the previous version of the 465P-VE (Whisper). I have the 465P-VE (WhisperII) and it has 33A on the +12V rail and a total max output of 460W. See my signature.

Did they actaully release a new updated PSU or did they just change the number on their previous model? Because both of them have the same model number
 
I guess Enermax just made a new revision but just kept the same numbering/lettering. On Enermax's website, my PSU is listed under the whisperII series. I didn't see any mention of WhisperII on the box. My PSU actually has a knob on the back for controlling one of the 2 fans to reduce noise, thus the Whisper designation I guess.  There are several models in the 465P series depending on features, active PFC or not, fan cotrol knob or not, etc. I believe the 465 PSU with 33A on the +12V rail has been out for quite a while now, at least over a year, probably longer.
 
Is this a good PSU for a K8N Diamond, Geforce 6800 Ultra SLI system?
http://www.hipergroup.com/products/hpu-4b580.html
 
Hi,

It certainly looks nice.
What counts are the amps on 12v, it doesn't say, I can't tell.

How about this one:
http://www.databutikken.com/no/default.php?artId=ASP520WBLA
http://www.databutikken.com/no/default.php?artId=OCZMS520W
Either 1 will be OK
 
I don't know anything about anything, but judging from this webpage, you can't just add 12v1 and 12v2 together.
It seems to suggest that the actual combined rating is less than the sum of the two combined - am I being stupid again or have I shown a glimmer of hope??
 
Waldo
That is correct.  Some power supplies have a power source for each of the 12v rails on a dual rail system and others use the same power source for both rails. ( One way the total 12v amps is the sum of both rails and the other may equal the amps on either rail or slightly more.)  That is why detailed specs are needed to determine a good power supply from a weak one.
 
I am building a HTPC.? I am looking for a powersupply. Here is what I plan on putting in it:

K7N2GM2-LSR
Sempron 2500+
DVD-/+RW
Western Digitial 320GB HD
Hauppauge PVR-150 PCI card
512 PC 2700 RAM

I may want to put in a second capture card later, and maybe a second HDD.

What sort of power do I need on 3.3/5/12V sources?

(TIA)
-Nicias
 
Hi
There are quite a few power supplies from the major manufacturers enermax-antec-ocz-akasa that will take care of your needs.  I would recommend a minumum of 30 amps on the 3.3and 5v rails with 20 amps or more on the 12v rail to allow for your future needs.  Get the best that you can afford since its reserve equals insurance against future needs.
 
Thanks for the advice. I looked at Antec and found some good PSU's. However, the cases I am looking into fall into two catagories:

1) Antec's Aria
http://www.newegg.com/Product/Product.asp?Item=N82E16811129146&ATT=Cases+Computer+Cases&CMP=OTC-d3alt1me
This has a custom PSU: 300W, 27/26/18A at 3.3/5/12V. That is slightly less then you suggest, but a standard PSU won't fit.

2)Various other mATX cases, these mostly come with STX PSU's, I can't seem to find STX PSU's from major companies. However, I have found some references which say I *may* be able to swap in an ATX PSU for the STX one that comes with the box. How plausible does this sound?

Again TIA,
Nicias
 
Take a look at some other cases.  The antec power supply will probably drive what you have now but are you going to be satisfied next month with what you have?  Better video cards-more memory- faster processor all require more power.  Also consider that micro atx cases lack the air flow of a mid tower or a full size case which can result in higher operating temps.  (Just some things to consider before your purchase-the final decision is yours)
 
I don't think that I will want more RAM or a faster Processor. The only thing I plan on adding is maybe another harddrive or a second capture card, however I am considering flexibility, so I will look at other cases. My reason for going with the microATX cases is because this machine will be living in a stereo cabinet, and so the size available is a limiting factor (18"Wx9"Hx17"D.) 

What about swaping the ATX in for an STX is that possible?

-Nicias
 
I am not familiar with the STX style power supply.  You can compare dimensions and wiring locations to check if it is possible.
 
Can anyone tell me the difference between the Antec TP series and SP series.  Looking at the specs they seems about the same.  Is there any major difference that would affect system stability? 

I currently have the Antec SP500w, and with all the junk I have in my system I'm thinking its time to go bigger. 
Its odd how it works great for a few weeks and then I come home and it wont boot, like I see it post and everything is good on the Status lights but no video, move around some connectors and it boots again, then repeat.  Thinking its starting to wear out.

Anywho, just wondering if anyone has any experience with the Smart Power and True Power models. 
 
One more thing to try to consider is heat. More heat inside the PSU equals less power. Many of the inferior power supply companies will show ratings even for continuous power at a temperature that is lower than you can exepct to see in a real world application. Also if you have poor ventilation in your case or have a high room ambient temperature you will lose some power.

As mentioned some very well respected brands plus I will add a few more PC Power and Cooling, Antec, Enermax, Seasonic, Corsair (currently rebranded Seasonic), Tagan, Fortron, OCZ, and Silverstone.

If you want to save a few bucks on a Power Supply try a CoolerMaster (Real Power or iGreen Power models) or a Xcilio. These two CoolerMasters are rated at their continuous power not peak according to the manufacturer. 

A high quality 450w Power Supply will be better than a poor quality 650w power supply.
 
Hello has anyone tried out the 
MSI TurboStream 600W ATX 12V V2.2/ EPS 12V/ BTX 600W Power Supply 90 
http://www.newegg.com/Product/Product.asp?Item=N82E16817701004
I know its dual rail, but its a EPS with the 8pin connector I need for my msi server mobo. I've allready purchased it so I hope its a goody!!!
henrythe9th
 
Back
Top