Vampyromaniac

I came across this page on PC Power & Cooling's website, and I'm wondering what you guys think of these points, particularly #'s 3, 6, and 8 below:

http://www.pcpower.com/technology/myths/

So what do you think?

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mkk

3. Edit: Whoops I misread that passage, so I disagree as follows: I've seen tests that prove that the extra interconnecting surface would have to be damaged or dirty to have a real negative effect. Maybe if one uses a large number of adapters in series on a single cable, but these engineered modular interconnects aren't a problem.

6. It's true that when a large amount of airflow is required, a single 120mm fan just not takes up more internal space but also causes turbulence in the air inside the unit. Air can also more easily get trapped in corners, though most manufacturers apply small venting holes at precise points in the PSU casing to lessen that effect. But the bottom end is that this only becomes a problem at times when no powersupply was going to be running "silently". If the 120mm fan doesn't have to rotate very quickly on a regular basis it wins because of the lower noise at low speeds. For PSU's designed for constant heavy loads a push-pull setup of two 80mm fans mounted vertically is the most efficient design. Such PSU's are often longer than the common standard and may be hard to fit in smaller cases.

8. I don't know if the mentioned loss of efficiency is correct when it comes to modern PSU design, but the so called multi-rail setup is with few exceptions really just one rail divided into several lines having separate ampere limitations. PSU's with true separate rails are rare. At time when users with dual graphics cards had problems with some PSU's, those PSU's designed with just one +12V line fared better. Today this isn't much to consider since all manufacturers have gone for the rout of splitting a single +12V rail into multiple +12V lines.

DudeBoyz

I'm 100% sold on the idea that a single 12v rail is indeed superior.

swimtech

Yeah, number 8 just makes sense - one 12v output rail can be regulated, overload protected, and impedence matched for low to extreme load handling more efficiently at less cost than three ( or however many...) and with fewer components. Take this water analogy - it's easier to drink from a fat hose than the skinny (albeit adequate for some...) stream from a water fountain. Remember, voltage is the speed of the water flow, amps is the actual quantity of water passing a point in a given amount of time.

Also, about the modular cables (#3), I agree for this reason alone - reliability over time. Sure, there's almost no losses across a new connector - it's tight, with adequate surface contact area - and there is really very little voltage loss over two feet of wire - that shouldn't be the point. The point is that over time, as heating and cooling within the case occur, the connectors themselves expand and contract and in differing ways because of the different shapes (male and female...). Engineering of the connectors over the past years has minimized this problem, but not eliminated it.

Eventually, the connectors loosen and the contact area within the connector decreases - thereby decreasing the current flow and increasing resistance across the connector that decreases voltage. In my work with electronic devices over the years, those using interconnecting modules/cables have much more trouble than those that don't. The interconnecting modules and cables can make a device easier to work on, or manufacture, but I'll take a wire soldered to its source for reliability over a snap on connector any day of the week.

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Grace

I'm sorry to ruin the mood guys, but all of that is just marketing. Sure PCP&C makes some of the best, if not the best PSUs around, but without marketing they too would fall.


A couple of examples, to support my opinion. I do not endorse multiple 12V power rails for my own reasons, but the above 'rules' state that when drawing a X amount of power out of a Z rated 12V line, you may end up with an Y amount of unused power. That's not true for any quality PSU out there, when any line is overloaded, the remaining lines will support it. True, there is a power loss, but nothing nearly dramatic. Another example could be the mention that modular power supply connectors may cause a large voltage drop on the line. That is true, but it certainly isn't as high as they mention when any connector of average quality or above is used and of course PSU manufacturers have programmed the voltage regulation circuits to compensate for that.


All in all...well, take it easy when reading what each manufacturer says.

DudeBoyz

Check this out at Enermaxusa.com:

http://www.enermaxusa.com/catalog/pr...3e06e75eda6fa6

They say they have two rails of 22a each. But total combined is only 32a.

It is on all of their products.

A single 12v rail is by far the best solution, even with a bit of noise generated when compared to multiple rail systems.

Dyre Straits

I'm sold on single 12V rail PSUs, too.

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Necrosis

While I agree in some part to what is said I also know PC & Power Cooling supplies are over hyped. I know of three that have died w/ no external reason.

Grace

That's not because of the two 12V lines, but because of the total output the 12V circuit can hold, and it's more than enough. For example, 32A out of the 12V line for the PSU you linked us to is already as high as ~390W, out of a 485W total output.

Most multiple 12V line 700W+ PSUs have four 12V lines of 20A maximum output each. So, if the 12V circuit could deliver all 80A, that would make them able to output 960W from the 12V line alone.


No matter how many lines you have, they can individually have a certain output which you NEVER can simply add them together, the total output of the 12V circuit is always lower.

DudeBoyz

Meh.

With a PSU rated at 22a per rail, it should add up to 44a total. It's like that 17" CRT thing - it's really a 16" vert measurement, not actually 17".

I'm all about a single 12v rail. No muss, no fuss.

I do think it sucks that on their Silencer 470:

http://www.pcpower.com/products/view...hp?show=S47ATX

Only has 26a on the 12v rail.

I never heard of these guys - is their stuff any good compared to Antec or Enermax? Why do they have FIVE different 510 class products in the same category?

http://www.pcpower.com/products/powe...h-performance/

I'm not so sure on their claim about 2 fans not being good. I thought the two fans both worked together to help pull air out of the case for exhaust? Not all 2 fan setups are spot cooling ones, are they?

Grace

Actually, PCP&C PSUs are considered to be the best of the type.



26A from a 12V line are pretty good for a 470W PSU; they are 320W worth of power, more than a system with 2-3 HDDs, a dual core processor and a high end GPU card can ever use. Anyway, even if it had a 40A 12V line, it could never output that kind of power when the total capacity of the unit is 'only' 470W. Let's be a little bit more reasonable.

DudeBoyz

Man, I dunno. I'm running tons of crap from my Enermax with 33 amps on a single 12v rail. Seems like some of the numbers just don't add up when I look at some of these multi-rail PSU's. Maybe Enermax just makes better PSU's than others. I don't know enough about the numbers and the fudge factors to be sure. I do know that when stuff works, everybody is happy, and folks seem to be having a lot of issues with Multi-Rail systems not carrying their weight, as it were.

What do you think about this statement they make:

Is that actually correct?

RoyBatty

Dude, have you actually read what Grace said in post #5?

DudeBoyz

Brain fade - sorry about that.

Odd that an actual corporation would make those claims and have them be false.

All these crazy numbers is freakin' my simple mind out. Doh!

Lowfat

Meh, 120mm PSUs are quieter, no matter what they say, definately over a loud screaming Delta fan that Pc P&C uses.

The .001 Ohm of resisitance a little alluminum connection is going to make in a modular PSU is absolutely nothing. Very bogus claim.

True single rail PSUs are better, but really doesn't make the biggest deal imo.

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Zelig

Most of the problems I've seen from multi-rail designs occur when manufacturers don't think out the layout of the rails properly, and what they're going to assign to the different rails.

Power supplies with an equivalent total amperage will generally perform equally, other factors equal. Single rail designs are going to be easier to hook up though.

FWIW, there are a few multi-rail PSUs where the total +12v A available is a simple sum of each rail. The Silverstone Zeus 850 watt has 18A on each of the 4 +12V rails, and 72A total.

However, PC P&C have some of the loudest PSUs in the market. Comparable Etasis or Silverstone power supplies match them for quality, and have much quieter 80 mm fans.

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Lowfat

Ya I don't think I've owned any other PSUs that had a single 80mm fan besides a PC P&C one, but good to know.

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Matth

1. Efficiency - 80-plus is good, nothing more to say... Cheap PSU s generally don't mention efficiency.

2. Wattage - damn lies and statistics, frequently a cheap "500W" would be only equivalent to a 400, 350 or even 300W drom a more reputable maker.

3. Modular cables - not a fan of them myself... if I needed to fit one back, you can bet it would have vanished into the junk. Since there is always one connector in line at the end, one at the start cannot be that evil though.

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5. SLI - seems to mean little other than having dual PCI-E plugs.

6. Not convinced either way, a 120mm blowing IN may give BETTER circulation and cooling than the lazy intake making up for an 80mm extract fan. also, from CPU heatsinks, it seems that the fan blowing into the heatsink is better. Also, it seems there are fewer "really bad" 120mm units.

7. Dual fan - more a fashion than anything, and many BAD units are dual fan. Unless the flow is so constrained that it needs the push-pull of two fans in series, the only real advantage is that the second fan is normally positioned such that it will serve as a CPU exhaust fan, though a seperate rear exhaust fan would be far superior.

8. I'd disgaree with the "lost power" issue, as the multiple 12V rails are rarely capable of 100% concurrent load - more to the point, many dual rails are only seperately limited, from a common feed, so any claimed advantages of dual rails are mythical in that case. The main point seems to be that a high current, single 12v is considered "hazardous", as it can deliver a lot of wattage into a short or partial short.

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Mary had a little lamb,
Her father shot it dead
Now Mary takes her lamb to school,
Between two crusts of bread

hackerx

isn't efficiency=total output/total input * 100?So in a 500W PSU output can always be upto to max but as efficiency decreases the amt of watts drawn by the PSU to generate
the 500W increases.Is that right or is my concept wrong?
and another question

if i were to buy an antec power supply of 500/550 watts
would u suggest me to buy a 500W PSU with no modular connectors,an 80mm fan and dual 12v rails of 17A each or buy the 550W PSU,with no modular cables,a 120mm fan and 3 12v rails of 18A each?
1.Antec EarthWatts 500W
2.Antec True Power Trio 550W

Its a real question,i'm in need of a new PSU

Zelig

Might be worth noting that there are several variations here. Some PSUs have single 80mm horizontal intake fans. Regardless of the effect on cooling, the placement of fans on the inside tends to produce less noise.

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Grace

That concept is correct. However, if (example) a 500W PSU can actually output 500W or if it can only draw 500W and deliver a 500W*efficiency % inside the system, depends on the manufacturer of the PSU. Most generic PSUs state their maximum power DRAW, not output. So a generic 500W PSU with 75% typical efficiency can output only 375W max. Tricky, isn't it?



The Power Trio 550W PSU is superior by every aspect, I see no reason why not to get that one.

DudeBoyz

Here's a link to a nice Single 12v Rail Enermax that might be worth a look:

http://www.newegg.com/Product/Produc...82E16817103437

Enermax usually makes great stuff.

DudeBoyz

I don't get why having one 80mm fan at the back of the PSU and another 80mm fan at the bottom of the PSU to help draw air up from the CPU area

Like the one in this pic here - up at the top left you can see there are two fans in the PSU:



Why would that not be a good configuration?

Grace

There is no such thing as 'good' or 'bad' configuration. Each configuration is ideal in certain environments and ineffective in others.

Zelig mentioned a single 80mm fan. That configuration is good, but not for powerful PSUs. It tends to be silent since the fan is inside the computer case and so the sound is lessened, but it is not the best possible method of cooling. This design is pretty much replaced now by the single 120-140mm fan design, which is still silent but moves a lot more air.

You mentioned a dual 80mm fan design. This is good for cooling in general, but two 80mm fans are usually above-audible levels. It is real hard to make a silent PSU with 2 80mm fans which doesn't overheat and/or gets noisy after some load. Very high efficiency PSUs benefit from this design, but not all of them.


Take into consideration that all PSU cooling configurations ultimately push the majority of the air they use for their cooling towards the rear of the case, no matter where the fans are placed.

DudeBoyz

That's a rather inflexible statement...

Thankfully, some PSU's, like the one I have, provide the ability to adjust fan speed. Mine has a dial right on the back.

Grace

It may be, but it is correct. "Flexibility" is not something I'm concerned about. Nothing is perfect. All configurations serve the same purpose, which is cooling the PSU, but each of them has certain limits.


Thankfully, the design of your PSU was dropped even by the company which invented it, because if you turn the fan down all the way and load the PSU due to the heat the efficiency and total output of the PSU will severely decrease and it will eventually shut down...barely at 70-75% of its rated full load. Also, running the PSU at higher temperatures will vastly affect the capacitor aging, which means that your PSU will not be able to output its rated power soon enough and as you can guess the lifespan is also severely affected. So, you have the ability to control the noise of your PSU, but you affect its performance at the same time. Wonderful, is it not?

Sorry for not getting too technical on that, I have a limited amount of time to spare.

Matth

Just reminded me...

Decent power supplies often have a "temperature controlled fan" - which varies speed according to the conditions.

Cheap ones often claim to have a "temperature control fan" - after all, the fann (blowing full blast all the time) does do something to control the temperature, as it would be damn hot without it.

__________________
Mary had a little lamb,
Her father shot it dead
Now Mary takes her lamb to school,
Between two crusts of bread

Judas

I don't know, i think the concept of Dual Rails was pretty much in consideration for a Single Video card connection to feed it a fairly stable source of power, and the other rail was for everything else.

Dual rails are horrid for setting up a performance power house of a machine, i ran into that dual rail issue with my OCZ 600 watt PowerStream whe attempting to run 2 video card (BAD BAD idea)

Triple rails sounds dandy to, 2 video cards and the rest seperately handled.

I think the whole concept of having multiple rails is to better provide Solid/Stable power to what it's connected to. I think it's also to prevent interferance. Multiple rails would be better suited for the Overclocker as well. Better stability, cleaner and less volitile power means higher overclocks.

The whole fan placements and size ordeal is slightly moot, considering IF you were running a PSU at it's MAXIMUM capacity at all times, you'd be having issues anyways, if you running slightly below it, you'll probably eventually run into issue due to PSU deterorating over time. IMO, if anyone is going to get a PSU, figure out how much you need using a few of the PSU caculators out there and then put on another 25% at least for safe measures and with the possibility of upgradeing it down the road. (IMO)

The modular issue, yes, the more connections you have, the more resistance you add, and the higher chance of something failing down the road as well.

If a modular psu is built, a good quality one should still last YEARS before it's connectors wear. And considering that majority of the time, enless a conneciton is disconnected and reconnected and messed around quite frequently, this should be a problem really.

The only thing that could be a potential issue is keeping the connection tight and solid, everytime a PSU is fired up, all the little screwed/pins/bolts whatever will physically move a bit, even while running depending on the sudden loads experience, a set of pins could be oventually pushed out simply by using it, but i'm seeing more modular psu with clips to hold the connectors in place much better then some of the loser standard slides.

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Grace

Actually, it all started by giving a separate 12V rail to the 12V CPU power cable. They claimed that the power towards the CPU was 'cleaner', 'free of ripple' and the CPU was more stable like that. I cannot say I ever agreed to that.

Also, no matter how many rails a PSU has, I never saw a single one feeding the 2 PCIe connectors from 2 separate 12V lines. Even 1KW+ PSUs offer a single line (usually the 3rd) to the PCIe connectors.

Zardon

I personally wouldnt touch a modular PSU for a variety of reasons. Also Judas, lay off the coke man, most of that post sounded like you were high or something, such a load of nonsense.