The Importance Of A Good Psu?!?

S

Shogo

Limp Gawd
Joined
Jun 1, 2004
Messages
389
Hi, i was about to buy a generic 400w psu to power a

athlon 64 3200+
120gb
dvd writer
dvd reader
512 ddr 400
3fans
ati radeon 9800xt

but i was quite not sure about the importance about a good psu and to calculate how many watts we do REALLY need.

Can someone explain to me the real impact of a good psu and if it change performance...

if you are able to change my mind, ill buy one :p
 
Cheapo PSUs can cause instability, random reboots, and possibly hardware damage because of electric surges, spikes, sags, and such. Quality PSUs tend to have better build, better components, surge/sag protection, and provide stable and clean electricity. Cheapo ones might be rated for 400 watt, but that might only be maximum output at something like 25 C, which is not the operating temperature in real use. So beware.

Antec, Enermax, PC Power and Cooling, Fortron-Sparkle, among others, are good PSUs (Antecs my favorite because PC P&C are expensive).

Do not skimp on the PSU! A $20 PSU might sound good now, but hundreds of dollars in potential component damage and random reboots and crashes don't, now do they?
 
one of my brothers had a cheap one, it went out and took everything else with it. dont buy a cheap one.
 
all the machines ive ever had have always been powered by generic psu's. Never had a problem. If you dont put large amounts of stress on it then i imagine it would be fine for its service life.

Id be curious to see large oem defect rates on them. Ive noticed no real issues so far.
 
Wixard said:
all the machines ive ever had have always been powered by generic psu's. Never had a problem. If you dont put large amounts of stress on it then i imagine it would be fine for its service life.

Id be curious to see large oem defect rates on them. Ive noticed no real issues so far.
Click to expand...


"How important is the quality of power you supply to your PC? This graph, which
shows the leading causes of data loss by category, gives you a pretty good idea"
http://www.pcguide.com/ref/power/
 
It amazes me how people are willing to spend large sums of money on computer parts and risk loosing all of it to a cheapo PSU.
A CPU depends on good clean ripple free power to operate, without it you are likley to experience BSOD's, endless problems which drive you nuts and cause grey hair. A good PSU will have a DC ripple of 1%-5% (the lower the better) this is often called "tight rails" Back in the good 'ol days of P, PII and PIII's a little voltage ripple wasn't a big deal. Now however the P4 is very suceptible to DC ripple. 5% is all that it can handle (Intel) and you are asking for it at 5% if you are not dealing with a quality unit. Cheapo units typically have +5% DC ripple, and, lead many a new builder to fustration, they always tend to blame the mobo or memory when infact the problem is an unstable, inadequate, power source. You get what you pay for is basically it. I for one am not going to risk my system on a $30 PSU. The second most commonm mistake is getting a PSU that is incapable of Sustaining a steady, stable output. Sure a PSU will put out 400W, but for how long and at what temp, often their ratings are very deceptive, unless you do a little reading or have a little knowledge of electronics. And, of course its putting out 400W but only 20 amps....not enough ! This also means that you have no headroom for any upgrades later on should the thing work.
Buy a good power supply, PC P&C is the best-but expensive (for good reason) Antec, Enermax are decent as well and all worth the money.....Just my 2 cents
twajetmech :D
 
here's something interesting... while I never experienced system instability... my 300w supermicro PSU started to get weaker...
how did I know? because burned cds had definate bands where the cd drive spun faster and thus the laser wasn't getting enough power :)
 
Ice Czar said:


"How important is the quality of power you supply to your PC? This graph, which
shows the leading causes of data loss by category, gives you a pretty good idea"
http://www.pcguide.com/ref/power/
Click to expand...
To save me the time, does it mention if its a utility failure (power company) or due to the actual psu itself?
 
Every power supply ive had explode on me has been a generic. I have not had a problem with any name brand PSU. Dont be a cheap bastard, just get something good, or youll regret it.
 
Well I have had 2 Antecs die on me within a year approx. One highpower and now a truepower 550 seem to act up. And all my friends who buy generic never have a problem :rolleyes: And the fact my previous generic PSU:s never broke either...

The first did kill a mainboard too it looked like. The other just died on it´s own. I am not sure yet I have only tested it with a PSU tester from PC Power and Cooling but it did behave irradic before I switched it to a PC Power and Cooling. Hopefully this will last more than a year. But it should be cheaper in the long run anyway since this has a 5 year warranty so I don´t have to buy new when it brakes.
 
oqvist said:
Well I have had 2 Antecs die on me within a year approx. One highpower and now a truepower 550 seem to act up. And all my friends who buy generic never have a problem :rolleyes: And the fact my previous generic PSU:s never broke either...

The first did kill a mainboard too it looked like. The other just died on it´s own. I am not sure yet I have only tested it with a PSU tester from PC Power and Cooling but it did behave irradic before I switched it to a PC Power and Cooling. Hopefully this will last more than a year. But it should be cheaper in the long run anyway since this has a 5 year warranty so I don´t have to buy new when it brakes.
Click to expand...

Its just luck of the draw when stuff like that happens. Antec is still the top tier PSU manufacturer for the price range and i havn't had one fail on me yet except for a fan which has started to make a noise. I'm replaceing it with a True Blue 480w this week though.

You have to look at the larger percentage of failure rates instead of just a couple bad instances you had. The Antec's have a 3 year warranty on them so you didn't have to buy a new one then ither.
 
Yeah I got the first Antec RMA:d for the truepower with some extra money in between but that don´t make it better. I rather have a 1 year warranty PSU that lasts for 3 years than a 3 year warranty PSU that lasts for 1 year.
 
Wixard said:
To save me the time, does it mention if its a utility failure (power company) or due to the actual psu itself?
Click to expand...

data loss to all the above, however like the figures below its derived from enterprise usage

computer down time breaks out along the lines of
cooling problems 8%
Power Problems 28%
Other Problems 64%

while Computer Expenses break out like
Power Supplies & Cooling Fans 2%
Other Components 98%
Source: Strategic Research Corporation

and thats enerprise usage, where UPSs and Backup generators are the norm
in addition those figures where derived before the current level of voltage sensitivity developed

looks like I should have choosen cut & paste instead of link :p

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Another Prime consideration in a power supply, especially one that is pushing a heavy load of HDDs, is that HDDs require upto 5 times their normal amp draw at spinup
(which is why SCSI conjtrollers often have a delayed spinup option for arrays, so they dont all start at once with the rest of the computer)

that coupled with the leading cause of dead RAM (after improper installation - ESD)
is power events, as the FSB becomes faster and faster, the quality of the onboard voltage regulators in conjunction with the PSUs transient response (voltage regulation under a dynamic load, overvoltage\under voltage) become critical in some configurations

its better to be safe on the PSU end, since ive rarely seen anyone test mobo voltage regulation :p

that goes along way towards explaining why person A with PSU X and Mobo D has no issues
while person B with the same PSU and a different mobo develops issues

-------------------------------------------- Cut & Paste from Corruption 101
Power Issues
There are three basic areas of power problems
1.Source Power Brown outs, blackouts, spikes\surges ect.
see > Power Conditioning and DIY UPS @ Dans Data, for the basics
In this category I would also place power issues due to pilot error, hard restarts and shorts, avoid both. Shutdown properly and pay attention when mounting your motherboard and routing power cables.

2. Under Power: Basically too many components for the power supply,
dont be decieved by wattage figures, its the amount of amps per rail that is really important.
See > Choosing the right Power Supply &
takaman's Power Supply Calculator rev0.61x
to determine the amps you need per rail

3. Voltage Stability Pretty much the all the following
[H]ardcore PSU info (Charts)
http://terasan.okiraku-pc.net/dengen/tester/index.html
http://terasan.okiraku-pc.net/dengen/tester2/index.html
(note the PC Power & Cooling, Antec, Ablecom, and Zippy)

In Japanese :p
But the graphs speak volumes
and the PSU are identified in English]



Continuous Power vs. Peak Power at Spin-Up
12V power profile (current vs. time) of an IDE/ATA hard disk at startup. You can see that the peak power draw is over quadruple
the steady-state operating requirement. The graph appears "noisy"
due to frequent oscillations in current requirements
Click to expand...

Peak vs. Continuous Power
Despite this extra capacity, it is still a good idea to not load up your system to the very limit of your power supply's stated power capacity. It is also wise, if possible to employ features that delay the startup of some disk drive motors when the PC is first turned on, so the +12 voltage is not overloaded by everything drawing maximum current at the same time.
Click to expand...
refering to the links above again
http://terasan.okiraku-pc.net/dengen/tester/index.html

note the consistent voltage instability at startup and shortly thereafter in those graphs

Winbond Launches New Bus Termination Regulator April 4th 2003

"Winbond Electronics Corporation, a leading supplier of semiconductor solutions, today launched the W83310S, a new DDR SDRAM bus termination regulator. The solution, new to Winbond's ACPI product family, is aimed at desktop PC and embedded system applications with DDR SDRAM requirements.

Computer systems architectures continue to evolve and are becoming more complex; CPU and memory speeds continue to increase ever more rapidly with every technology turn. More and more high current/low voltage power sources are required for PC systems. This is particularly true for high-speed components such as CPU, memory, and system chipsets. The performance of these components is highly dependent upon stable power. Therefore, motherboard designers require accurate, stable, low-ripple and robust power solutions for these components.

Many system designs use discrete components to implement bus termination functions. This approach creates several problems including poorer quality load regulation; higher voltage-ripple, increased usage of board space and inconsistent designs when different discrete components are used."

and just to reinterate this point one more time
http://www.anandtech.com/showdoc.html?i=1774&p=8
"the majority of damaged RAM returned to memory manufacturers is destoryed by fluctuations in the voltage."

the transient response is the critical measure, unfortunately its not a metric that is commonly supplied with the PSU specs
(this seems to be slowly changing, as some manufacturers are supplying the transient response now)

Transient Response: As shown in the diagram here, a switching power supply uses a closed feedback loop to allow measurements of the output of the supply to control the way the supply is operating. This is analogous to how a thermometer and thermostat work together to control the temperature of a house. As mentioned in the description of load regulation above, the output voltage of a signal varies as the load on it varies. In particular, when the load is drastically changed--either increased or decreased a great deal, suddenly--the voltage level may shift drastically. Such a sudden change is called a transient. If one of the voltages is under heavy load from several demanding components and suddenly all but one stops drawing current, the voltage to the remaining current may temporarily surge. This is called a voltage overshoot.

Transient response measures how quickly and effectively the power supply can adjust to these sudden changes. Here's an actual transient response specification that we can work together to decode: "+5V,+12V outputs return to within 5% in less than 1ms for 20% load change." What this means is the following: "for either the +5 V or +12 V outputs, if the output is at a certain level (call it V1) and the current load on that signal either increases or decreases by up to 20%, the voltage on that output will return to a value within 5% of V1 within 1 millisecond". Obviously, faster responses closer to the original voltage are best."
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and slightly more than half the ESD & Electromigration Rant

Latent defects caused by ESD in any IC (and they are just everywhere from HDDs to NIC, CPU, RAM ect) are massively underated as a cause of problems. If you have eliminated power fluctuation problems (PSU voltage regulation and power conditioning) and still experience a component failure, odds are that it was a latent defect, either from installation, or one that wasnt caught during manufacturing.
the membership displays a cavalier attitude towards this issue for 2 reasons, RMA's are pretty easy, and they rarely employ the same component for its fully rated lifespan, upgrading before the eventual premature failure becomes appearent.

But
a latent defect, not only effects the lifespan, it degrades the performance of the IC as well, and is often the difference between the "Golden Chip" benchmark leader, the norm, and "why cant I get the same OC as this guy? Ive got the same components"

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Electromigration is the mechanisim that typically first degrades and then kills IC Chips (Integrated Circuits)

Semiconductor Electromigration In-Depth @ DWPG.com < the totally understandable link (if somewhat dated these days in particulars)

What is electromigration?

Harris Semiconductor Lexicon of technical terms puts it this way:

"Motion of ions of a metal conductor (such as aluminum) in response to the passage of high current through it. Such motion can lead to the formation of "voids" in the conductor, which can grow to a size where the conductor is unable to pass current. Electromigration is aggravated at high temperature and high current density and therefore is a reliability "wear-out" process. Electromigration is minimized by limiting current densities and by adding metal impurities such as copper or titanium to the aluminum."

Electromigration is an effect that occurs when an extremely dense electron flow knocks off atoms within the wire and moves them, leaving a gap at one end and high stress at the other. In a chip, the formation of such a void will cause an open circuit and result in a failure. At the other end, the increase of stresses can cause fracture of the insulator around the wire and shorting.
Click to expand...

Electromigration and Voids @ Cornell
Electromigration Simulator @ MIT
processing temperature -- increasing the processing temperature will increase the initial tensile stress present in the line due to thermal mismatch, thereby leading to earlier failures. To neglect the thermal stress, set the process temperature the same as the test temperature.
test temperature -- increasing the test temperature will dramatically reduce the calculation time since diffusivity is follows the temperature by an Arrhenius relationship.
Click to expand...

the Arrhenius equation

roughly translating to this rule of thumb
Each 10°C (18°F) temperature rise reduces component life by 50%*.
Conversely, each 10°C (18°F) temperature reduction increases component life by 100%.

however there is more to it
http://www.triquint.com/company/quality/faqs/faq_07.cfm (caution heavy wading)
"Electromigration mechanisms are accelerated by current density as well as temperature. The general relationship is sometimes referred to as Black's Equation. Just as with the Arrhenius equation, we can observe the electromigration effects on lifetimes using a graphical approach."

so, both elevated temperature, and voltage, can cause voids to form in the circuits of any chip, a problem that becomes more and more important as the number of atoms that comprise the width of that circuit decrease, (that first link was written when the manufacturing scale was at 0.18 microns we are now at .9 microns (90nm) with some chips) in addition the clock rates that the power is cycled through is all that much higher as well, making the chips all that more suceptible to ESD, voltage irregularities and temperature.

In short, Im very serious about my ESD precautions, power conditioning, power supplies and my thermal solution (under 40C CPU at full load w\ 30C SYS minimum) , and considering the price Ive paid for my workstation I want to squeeze every last hour out of it that I can, unlike a gaming rig, that may or maynot find another role in life once its yesterdays news, mine will be retired to a nice animation cluster to live out its full lifespan, but these cautions are just as important for anyone aspiring to a record overclock, or killer benchmark ;)
 
I have been building, upgrading and repairing PCs for about 17 years. In fact, I've never bought a single pre-assembled rig in my life. Without question, the number one problem I've seen over the years has been with cheap, no-name power supplies.

I have a big cardboard box of them, many of which are either toasted, or never used, (because of lack of confidence), and were pulled from otherwise decent cases, I cannabalize them for a fan every now and then. Most of the units have frighteningly shabby construction as compared to a quality supply, and invariably, there are locations of dozens and dozens of components silk-screened on the circuit board of these units that are missing. I recently replaced a noisy fan in an Enlight unit. Every component was present and accounted for, and the care and quality of the construction was plainly obvious. And don't even get me started on the voltages and AC ripple. I'm not an electrical engineer, but I'm no n00b, either. I can see the difference with the oscilloscope and VTVM I have.

Those who have said you shouldn't entrust hundreds and hundreds of dollars worth of hardware to a generic power supply know what they are talking about. I wish more emphasis on testing these things was established by a good hardware site, preferably [H]ardOCP. Somebody needs to set some sort of testing regimen, and start holding these PSU manufacturers feet to the fire.
 
Rhenna said:
. Somebody needs to set some sort of testing regimen, and start holding these PSU manufacturers feet to the fire.
Click to expand...

http://hardforum.com/showthread.php?t=758628

I contacted PC Power & Cooling with a recommendation that they extend Mike a PSU for testing, the tech deopartment said they would forward the request to marketing (which I took as a good sign, since I sent the email to sales)

Mike has the only rig, and more importantly comprehension of how to use it
that ive seen in an English Language site

Ive been trading a few emails with him, and his equipment and reviews are just going to get better ;)
 
WOW, that is great news, I look fwd to reading the articles when they come out....you will also notice a lack of reviews for PC P&C on most sites that do review PSU's....hmmmmmmm I wonder why....lol
twajetmech
 
To expensive hehe

There is a whole bunch if you are looking though.
 
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