It's the one lots of people have been asking about: Q-Technology QT-02300 PSU -- http://www.silentpcreview.com/goto.php?t=s&id=35&a=1 You're welcome to continue this thread for feedback, etc...

Nicely done, Mike, and provokes a surprising conclusion:

The Seasonic SS300-APFC is by far the most efficient of the bunch. If we assume the Q-Tech PSU was 65% efficient, then the entire system used about 82.55 watts of DC power (127*.65), and we can derive the following data for the rest:

Q-Tech: 65% efficient, 44.5 watts from PSU heat (127-82.55)
Zalman: 66.5% efficient, 41.5 watts from PSU heat (124-82.55)
Seasonic: 72.4% efficient, 31.5 watts from PSU heat! (114-82.55)

This makes the Seasonic the hands-down efficiency winner, running 24% cooler than even the Zalman! This is a huge endorsement for the Seasonic for anyone willing to open the PSU and use their own undervolted fan for the ultimate quietness.

Also, it shows that the Zalman is NOT as efficient as claimed, which makes one wonder why it's $15 more expensive than the Seasonic.

PS: Considering the PC in my article uses an older Q-Tech PSU without active PFC, I can definitely construct a better system in the future based on the Seasonic APFC.

Your conclusions are correct, Leo, given the data, but as I've mentioned, there ARE usually sample variances that make generalizations difficult unless at least a few samples of each model are examined the same way. Like if the QT was a -5% performer and the Seasonic a +5% one, adjusting for those variances, both would end up at 120W total power. If you say 5% is too much & adjust for 3%, then it be 123W for QT, and 117W for SS. Still a pretty small difference.

FIY, 117W IS what I get with the 2nd sample SS sent -- the only PSU maker to send 2 as requested.

In any case, it is true that my QT sample runs hotter than either Seasonic sample. Maybe I am being a wuss but it is difficult to generalize with just one QT sample which might not be normal. Q-Tech says the coil whine is totally abnormal. They're trying to sort out what might be causing it. Will keep you posted on that.

Mike,

Your point about small sample size is well taken. However, statistically, what are the chances that all three units are fringe performers? Let's examine the results a little closer, and see what conclusions are probably legitimate. I admit the validity of my arguments heavily depend on the amount of deviation of PSU's from the norm, but I will at least assume some sort of bell curve distribution.

The Zalman sample is clearly far behind the Seasonic sample. It is extremely unlikely that the Zalman unit accomplishes its claimed 72% under small load (this would imply the Seasonic achieves an insane 78.3% efficiency). So the reasonable conclusion is that both units are much lower. EVEN IF the Seasonic was hand-picked as a top-efficiency unit, the Zalman is STILL either an altogether inefficient unit (contrary to Zalman's claims), or you simply got a lemon. What are the chances that BOTH of the following are true?

1) Seasonic employees either went through the pain of measuring and picking the most "efficient" unit of the bunch, or luckily picked an extraordinary sample (not that likely)
*AND*
2) Your Zalman sample is a complete lemon (not that likely)

Given the chances of both coinciding is fairly low, I think it is highly probable that:
1) Zalman isn't as good as claimed, and
2) Seasonic is, if anything, at least a more efficient choice than the Zalman

Even with a sample of 1 each, conclusion #2 seems very probable. I won't even discuss Q-Tech since it never contended for the efficiency crown.

I understand your reluctance to jump to conclusions and needlessly alienating PSU vendors. Maybe if you explained the probabilities involved, however, then your credibility would not be tied to such statements.

PS: I am also not sure about whether the 5% deviation figure should be applied to TOTAL system power, rather than PSU's heat from inefficiency. If total system power can fluctuate by 5% depending on luck of the draw, this implies 15% fluctuations in the actual heat produced by the PSU. Is that a reasonable amount from the same model? You have more experience with PSU's than me, so I wonder what you think about that.

Sorry to make the confuse, please refer to following explain:
1. The reason why most of PSU manufacturer just put 65% efficiency on their specification just to meet the minimum requirement of Intel power supply design guide
http://www.formfactors.org/
2. Normally the efficiency will be present as minimum and typical, the minimum efficiency was defined by statistic lower limit and the typical efficiency was the average number

Thank you for the excellent Q-Technology PSU review, Mike Chin. I own this unit (QT-02300) and indeed it does raise my mainboard temperature (as reported by software -- the Asus Probe) by about 2-3 degrees Celsius compared to my previous 300W AOpen PSU. But I run my case completely open (no sides, no top) so I think that helps with cooling and I don't use any case fans. Although I might try adding a case fan now, particularly considering it's summer in North America.

I can also say there's a "coil whine" in my unit, but it's intermittent! Sometimes it's there, sometimes it's not. Or maybe I'm imagining it. I'll keep listening as I only got the unit yesterday.

But I like the low fan noise. And I think the low exhaust helps with lowering the noise. I remember what I really disliked about my AOpen PSU was not so much bearing noise but the air "whooshing" sound out the back.

But is the Q-Technology quality rating (7) marked down from the original 8 because of coil whine or because of inefficiency, as seems to be the main topic of this thread?

Interesting points Leo. In answer to your last question, I repeat, the second sample of the Seasonic 300W did hit 117W, which represents +3%. 15% sounds like a lot but the actual heat is ~6W (based on 40W). I don't know whether 5% is realistic because although I've looked at many PSUs, I have not seen more than 2 samples of the same model. One reason I chose 5%: that is the tightest tolerance given for PSU line voltage regulation.

Mike, I apologize for overlooking that point. I'll never be a speed reader

So going by previous guesstimates, the two Seasonics would exhibit 70.5 and 72.5% efficiency. This still appears to favor the Seasonic units, even if the average efficiency thus far (71.5%) is ~1% lower than I may have previously predicted.

The real efficiency of a power supply should be " Power factor * internal efficiency"

Power factor (PF) was the factor that how we utilize the power from wall (or we say power plant)

PF=working power/apparent power
working power: the useful power we get from AC input
appaarent power: the power provided by power plant
reactive power: the useless power but we still pay for it

Efficiency=system load (PSU output)/ input power (working power)
system load: the PSU output
input power: the useful working power from AC
disappear power: All become heat

EX: a rated 300W PSU with 99% power factor and 75% efficiency (call it A) VS another 300W PSU but 50% power factor and 65% efficiency (call it B).
A: (PF:99%, EFF:75%)
working power: 400W
heat: 100W (why we need fan)
apparent power: 404W (what we paid )
reactive power: 4W

B: (PF:50%, EFF:65%) normally the power factor from the wall was 50%
working power: 461.5W
heat: 161.5W
apparent power: 923W (what we paid )
reactive power: 461.5W

Please refer to http://www.comsprague.com/power2.htm they make a simple description about power factor

Vincent, thanks for the info. Since Mike used an external measurement tool, however, doesn't this mean he was already measuring the apparent power? In other words, shouldn't the KillaWatt device give the ultimate measurement of power usage?

Also, there is something I don't understand: in your Example B, where do the 461watts of reactive power go? Don't they become heat as well? In other words, doesn't the computer in Example B ultimately dissipate the entire 923W?

PS: For the record, Zalman reports .94 power factor, and Seasonic reports >.95.

Hello Leo V:
The reactive power which sustains the electromagnetic field we could not feel it without equipment, I'm not sure the power meter Mike used could measure apparent power or power factor.

I think coil whine was mentioned as the reason for the markdown. I think it IS possible that the combination of components in the P4 test platform may be demanding. I've had a much more serious problem with coil noise in 2 Antec TP380 samples tried on the same test platform that still has not been resolved.

Demanding, huh? Okay, if you say so, but the main reason I bought the Q-Technology PSU was based on a recommendation from a website (www.3dgameman.com) and he said he was running the unit in his P4 [email protected] with several drives and it held up very well. He didn't mention coil whine in his (video) review.

But you hear it in yours!

If every PSU hooked up to this test system exhibited coil whine, then the system would not be acceptable. But of nearly 10 PSU modesl tried, only 2 models have shown any coil whine at all. As mentioned in the article, the Q-Tech sample will be tried on other systems to check on coil noise & this will be reported. As I wrote, it is variable, ranging from not audible to plainly audible -- depending mostly on load, I believe.

My question about the 3dgameman review is how loud the overall system was. With several drives (probably not Barracudas) and possibly several ordinary 12V fans and a mega HSF, even if the PSU did whine, do you think he'd notice?

Yes I do. But it's intermittent. Sometimes it's audible, sometimes it's not. You say it's based on load? Okay, I'll look out for that. This issue of coil whine is completely new to me, I didn't know it existed until I started reading silentpcreview.com this week.



I don't know if you saw the actual video review from 3DGameMan.com, but he was running the PSU outside the case on a wooden table, probably without his noisy disk drives. But in any case, his review wasn't thorough like your 2-page review was, Mike C, so I trust your readings and opinions. I was just confused as to how "coil whine" was a "quality" issue. I figured the issue LeoV was talking about with efficiency seemed more of a "quality" issue. But anyway, thanks for the detailed comparison and assuring me that I bought the quietest PSU around (occational coil whine and wattage inefficiencies aside :)

Well you have a point there. I am no power supply design expert, and I don't KNOW that coil buzzing is a "quality" issue in a purely electronic sense. It is a quality issue if you're concerned about noise, and it may be more than that. My assumption, which may be wrong, is that coil whine in a PSU is a sign of stress under load due to less than ideal circuit design or implementation. TerryW, an electronics tech who has lurked about here, may be able to shed some light on this. Or Vincent (from Seasonic)

BTW, Silicon Acoustics, the web retailer, mentions the absence of coil noise in their description of some PSUs.

I am not pleased with q technlogy psu either. But I dont care i just give away to friend and get a better quality and less noisy.

I can always send it back but I am to lazy. I know 3 guys that tried q technlogy psu all think they are to noisy. They are geting a bad repution by alot music computer users.

People dont recomend it after buyin it. It is almost quiet. But a long way from silent.

BW

Okay but compared to what? Seasonic? A fan-less PSU? I'm honestly very pleased with my Q-Tech QT-02300 unit, but I'm not a "music computer user."

Stress under load, eh? Okay, makes sense. I find that my QT-02300's coil whine is absent more often than it is audible. Which is satisfactory for me.

I find that I need to reply to the "coil whine" issue. In my experiences as an electronics technician (for a western Canada electronics control manufacturer), I have found the coil whine can be attributed to many things.

I would assume these PSU under review are designed to the ATX form factor (http://www.formfactors.org/developer/sp ... atx2_1.pdf) and/or are ATX P4-rated.

A breif PSU design overview:

The PSU design is, as I mentioned in another article (Thermistors for Fans), a switching power supply. Such a switcher operates at around 40,000 Hertz. This frequency is above the human hearing range and should be inaudible.

This means the transformers inside the PSU operate at this high frequency. However, the coils are designed to store the energy from the PSU outputs, should be 'seeing' pulsed DC from the PSU outputs and not reacting to the high frequency. Any noise eminating from the PSU (other than the fan) would be heard as a whine (high-pitched vibration).

Therfore having said all this, the possibilities for coil whine could include:

1) Inefficient PSU design.
2) Defective coils or transformers. The whine could be caused by loose or damaged ferrite cores, or loose wire windings around the ferrite cores.
3) The PSU does not have the required capacity for intended loads.

One sure way to isolate where the noise is coming from, is to use a trick I learned during automotive classes in high school (more than 30-years ago). Take a metal screwdriver (any blade), carefully place the blade on the suspect noise maker and place the handle next to your ear. The noise will travel up the screwdriver and can be easily heard in the handle. This is an easy diagnostic tool to determine which part is making the most noise.

Of course, the PSU is fully operational and the cover is removed. Extreme caution needs to be exercised as there are very high voltages and currents in the PSU. If you use the screwdriver trick, I would highly recomend wrapping the exposed metal shank with electrical tape.

If the whine is caused by the transfomers, nothing can be done (except to replace PSU). However, most coils have some form of glue or epoxy on the outside of the wire windings. The intent of the glue or epoxy is to reduce or eliminate the vibrations within the coils. If the coils do not have the glue or epoxy, you could try that.

Be wary when applying glue or epoxy: too much could cause the coil to overheat, too little will not reult in any effect. A tight balancing act!

Failing all this, you might consider contacting the PSU vendor for a resolution.

Two other topics:

A) When a manufacturer or vendor sends (the company I work for) components for evaluation, I always ask for at leats 5 devices, from various manufacturing batches to fairly evaluate the products. Albeit, the components that are sent can be small components, such as switches, LED's, power supplies (linear & switchers) and larger devices such as LCD modules, input & output modules, etc.

I can appreciate that computer PSU manufacturers will be inundated with requests to supply sample products from all kinds of testing organizations. In the industry that I have worked in (over 25-years), the company I am employed by is an industry leader in innovative products.

Our vendors are ALWAYS inundating us with TONS of sample parts and is in the vendors best interests for keeping companies like (the one I work for) up-to-date with technolgy. These components or assemblies are write-offs from a sales perspective, but could lead to future sales and industry acceptance.

In the long and short of it: the PSU manufacturers / vendors should be providing adequate samples to make reasonable assesments. In all honesty, I doubt if I could evaluate a component based upon one sample.

B) Has anyone seen a PSU manufactured with the optional 6-pin wiring connector (per the ATX specifications version 2.1)? On pages 22 & 23 of this specification, pin 2 (FanC) can control the PSU fan. It would be easy to develope a small switch with resistors to attach to this connector.

Good luck and good computing.

TerryW

I have talked with my father, who is a physicist, about what happens to reactive power. Turns out that you pay for reactive power, but it doesn't produce any heat because it returns to the wall socket it came from, put plainly. The power meter, however, only records incoming power and that is why you still pay for it.

I found that the Kill-a-Watt device can track the exact power factor of the PSU. However, since both Seasonic and Zalman have near-identical power factors, I doubt this will affect how they stack up against each other. In fact, I suspect that its (K)W reading applies to only useful power, i.e. power that turns into heat. If that's true, then our entire discussion about power factors has no relevance to Mike's results at all.

Okay thanks for the explanation TerryW. Although I still don't understand why my Q-Tech buzzes sometimes and most of the time it's quiet. Load? Strange, because it can buzz during light load, and not buzz during Unreal Tournament gaming.

Okay.

The buzzing could be caused by a defective part. It could be a loose wire winding on one of the coils. You might try and resolve the issue yourself. Find out what the computer is doing to cause the buzzing, is it consistant and find the component causing the buzzing. Put on a glove and grab the suspect part. If applying a small amount of pressure fixes the buzzing, try some glue.

Good luck.

TerryW

All of which would involve voiding the warranty on my Q-Technology unit, and I'm not hardcore enough to open power supplies yet. Plus I find that my QT-02300 power supply buzzes for about about 10 - 15 minutes each day and that value seems to be decreasing as days go by.

Because coil buzzing can be caused by specific interactions, you might try plugging the PC into a different AC outlet or surge suppressor or UPS & see if it changes.

Good suggestion MikeC.

As I live in B.C. and my insurance provider is ICBC, a similar story comes to mind. Quite a few years ago, when computers were the thing for inurance companies, quite a few new computers were being installed into the North Vancouver ICBC tower.

The computer network guys had the foresight to upgrade the wiring for more computers. However, ICBC had lots of problems with the large fuses that protect the power-factor correction in the basement of the tower. The fuses kept melting!

Power-factor correction is required for companies with large inductive loads & such demands. I.E. Large motors, air conditioners, etc.

The cause of the problem was directly associated to the switching PSU designs in the computers and the immense quantities. ICBC had to spend a huge chunk of change to update the AC power lines to operate all those computers.

I am not saying this could be the cause, rather I am saying that if a household or business has multiple computers on the same power line, the computers can affect one-another.

For the record: Households and most businesses will not have power-factor correction, as most homes & businesses do not have large inductive load demands.

A few questions now come to mind:

1) What is the AC powerline voltages?

If the powerline was low (around 100VAC), the PSU has to work harder to generate the same load capacity, if high (125VAC), the PSU needs to limit the load capacity and regulate.

2) Is the power cord and plug in good condition?

Faulty power cords & plugs can be a hazzard and must be replaced.

3) Is the wall plug connections for the power cord in good condition?

A faulty earth ground connection can wreck havoc on compuiter PSU. There is an inexpensive ($5 to $15 CND) wall plug tester available at most electrical supply stores. This device simply plugs into the wall plug and provides 3 indicators which indicates whether the circuits are working and what is defective. Any defective plugs must be serviced by a qualiied electrician. Also, nothing should be oplugged into that wall plug.

4) What is the ambient room temperature?

If it is hot, the PSU works harder to acheive load capacity and regulation.

5) Does the buzzing stop when room cools down?

6) Is the buzzing dependant upon what is being done at the specific time(programs running, games, high memory useage, etc.)?

7) Is the buzzing happening at any particular time of day?

In most electrical / electronic applications, if something is going to go wrong, it might happen at times when the most demand is on the AC powerlines. I.E. 7AM to 9AM = Breakfast demands caused by stoves, fridges, microwave ovens, etc. 5PM to 7PM = dinner time demands. 8PM to ?? = lights, heat, and/or all the above.

How may computers on the same power line?

9) What kind of surge suppressor is being used?

If the surge suppressor is a transformer based unit, the reactive power from the PSU could be reacting with the transformer in the surge protection.

If all else fails....

I would suggest speaking with a manufaturers technician and/or return the unit. In my technican oppinion, the PSU should not make noise. To me this is a sign of a problem.

Good luck.

TerryW