Five Power Supplies Compared

EconolineCrush writes "Tech Report has done up a comparison of five high-end power supplies that looks at actual voltage levels and AC ripple content. The article also takes a look at environmental factors like noise levels and each power supply's impact on system temperatures. Think power supplies with like wattages are created equal? Think again."

Comments

older tests :

[Anonymous Coward]

http://www.tomshardware.com/howto/20021021/index.h tml

21 power supply tested here :)

Re:So what difference does a good power supply mak

[neodymium]

Good PSUs contribute a lot towards system stability. For example, a moving head in the HDD causes current transients (so does a CPU switching between normal operation and power saving mode). Bad PSUs have huge voltage drops during these transients, good PSUs can buffer them quite well. These transients can cause anything between nothing and total system crash.

Also, the ability to filter noise out of the AC helps with stability...

Re:So what difference does a good power supply mak

[saskwach]

In a cheap power supply, you can get inconsistent voltages, crazy transients, crosstalk, and if the power demand from one line goes up it can drop the wattage/voltage on the other lines. Cheap power supplies are also frequently noisier (sound too) than high end ones and run less efficiently (read: hot) than better designed, more expensive power supplies. Think about it: your computer operates because of well controlled voltages. If your voltage drops by 2V, some transistors will go into their linear range and cause crazy crazy crap to happen.

Re:So what difference does a good power supply mak

[LookSharp]

See my reply here.

The reason they check the voltages so closely is that one you start falling out of the 5 or maybe 10% tolerance zone for many components, over-voltage will cause overheating, lockups and early failure, and undervoltage also frequently causes lockups and occaisionally failure.

Also, some supplies give you a total wattage without breaking down where those watts can go. When you're dealing with processors that pull 80 watts at peak, you REALLY don't want a cheap supply that is busy sending all available watts to 5 and 12 volt channels to power drives.

Re:So what difference does a good power supply mak

[Tmack]

Having worked at a computer repair shop, I can assure you, YES there is a BIG difference between cheap PS's and quality ones. Cheap ones will last only a few months on any newer system, they might last a few years on older ones. Blown PS's was one of the most frequent repair jobs, and anytime someone requested the cheapest part to replace it with, I knew I would see them in a few weeks. They also affect System stability, if the PS cant put out the power the computer needs, it will crash (and the PS will burn itself up sooner as well). Got frequent blue-screens/sig11's and cant find anything wrong? Change your PS to a better one, there's a good chance thats the cause. Go to a local computer shop and pick up a cheap one in one hand and a good one in another, you will feel the difference. I always recommend Sparkle (there are some re-branded ones made by sparkle, will have SP in the model #) and HEC, and although I havent RTF yet, I would bet one of those is at the top, and the other is close to it.

Another thing to consider when buying a case.. the PS they put in cases are the CHEAP kind, unless they specify what kind it is, I generally expect to replace it within a year. A few years ago I had one of the dual socket370 BP-6 boards, it refused to boot on the PS I had that came with my case (Enlight none the less). I swapped it to a sparkle 300watt and have had no probs since.

This was also recently covered by Tom's Hardware, and earlier by a few other sites. The sparkle and HEC normally blow away the rest, with their 250w beating the specs for most 300+w, and even being able to hold 300w operation themselves.
just my $.02

Tm

Re:So what difference does a good power supply mak

[Jucius Maximus]

"Is there something that these power supplies contribute towards overall system stability that "cheap" ones don't? Are they really worth the money?"

If you've got weak voltages on the PSU rails, it can kill your HDDs. Some people lose drive after drive and never consider that their voltages are out of spec. Also, if your cheap PSU shorts on the DC side, say goodbye to your drives and maybe your motherboard and everything plugged into it.

PC Power and Cooling

[EchoMirage]

Why is it that every time these "high-end" power supplies get compared, the most high-end one always gets ignored? PC Power and Cooling has long manufactured the world's best power supplies. They're the Ferrari or the Moto Guzzi of the power supply world. Yeah, lots of Asian manufacturing firms make OK power supplies, but PCP&C's stuff is the only company that makes boards that the major motherboard manufacturers highly recommend and use exclusively in their own tests. Why does such an obvious high-quality product always get ignored?

Four missing Parameters

[mykepredko]

I'm not a power supply designer, but I do have some experience with system power supplies and their affect on system operation/reliability. If I were deciding upon a power supply for my system (or product), I would carry out the same testing as in the article, but also measure the following four parameters:

1. Initial Power Up overshoot/ringing/stabilization. I would hope the supllies powered up with a basic RC curve "POWERGOOD" becoming active when each of the supplies are within 1% of their targets.

2. Transient response. This is different from the "Load" test, it would look at how the power supply worked when it went from minimum load to maximum load and back again. Say starting up the disk drives, CD-ROM and change the fan speed at the same time.

3. Transient response across supplies. What happens if there is a large transient on another supply. The different power outputs in modern power supplies are not as separate as you might think.

4. Power down characteristics. Again, this should be a smooth RC curve with no overshoots or ringing. The high power positive voltage outputs should never go negative.

The first and last parameters will be an indicator of how "gentle" the power supply is on the components and whether or not there is any danger of having them overstressed. The middle two parameters would indicate how reliable operation of the PC would be and whether or not you would get power supply induced lock ups or glitches.

Power supply design is more art and component management than strong engineering application. Modern PC power supplies really are a result of iterative cost reduction and learned experience. A lot of "common sense" ideas are just plain wrong when applied to high current output switching AC/DC converters: I have learned that heavier is not always better and is often an indicator of an inefficient design. Fires are not uncommon in PC power supply testing and development and choosing the best power supply design is often a case of figuring out which company could best understand what the ashes were teling them.

myke

Re:Power supplies

[swordgeek]

People said that about speakers too. Heavier construction meant less vibration-induced distortion.

So one company poured concrete in the base of their speakers. Even after the reason for their weight became clear, people actually still believed that they were the best speakers for that very fact alone.