Solved Is it just me, or are power supply calculators just completely unreliable?

bobkn said:

Some of us prefer to get PSUs with a single +12V rail.

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My information is not up to date as this is only what I remembered since I haven't really kept up with parts since 2009 or so.

Almighty1 said:

My information is not up to date as this is only what I remembered since I haven't really kept up with parts since 2009 or so.

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Years ago, some PSUs with multiple rails caused trouble due to some motherboard setups exceeding the allowed power draw on one of the rails.

I hope that's of the ancient past.

Single rail PSUs never had that issue, obviously.

bobkn said:

Years ago, some PSUs with multiple rails caused trouble due to some motherboard setups exceeding the allowed power draw on one of the rails.

I hope that's of the ancient past.

Single rail PSUs never had that issue, obviously.

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Yeah, my knowledge is from the ATX days. Not sure how it works with the 12V single rails. So how does it handle things that require like 5V or basically anything less than 12V?

Almighty1 said:

Yeah, my knowledge is from the ATX days. Not sure how it works with the 12V single rails. So how does it handle things that require like 5V or basically anything less than 12V?

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Not sure what you're asking. Single rail PSUs are still ATX. My current main one is ATX 3.0, which includes the 12VHPWR port for the current nVidia GPUs that use the (too) small 16 pin PCI-E connector.

thanks everyone, lots of good information

bobkn said:

Not sure what you're asking. Single rail PSUs are still ATX. My current main one is ATX 3.0, which includes the 12VHPWR port for the current nVidia GPUs that use the (too) small 16 pin PCI-E connector.

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I mean there are devices that uses like 5V, not sure if that still applies though. Since you said Single rail have a +12V rail, so how does it handle things that require less than +12V as the nVidia GPUs uses 12V's but what about other things that uses less than 12V.

Almighty1 said:

I mean there are devices that uses like 5V, not sure if that still applies though. Since you said Single rail have a +12V rail, so how does it handle things that require less than +12V as the nVidia GPUs uses 12V's but what about other things that uses less than 12V.

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It means that there is a single +12V rail, rather than multiple ones.

The other lines (5V, 3.3V, etc.) are present.

Here are some of the specs from a Seasonic model:


I don't have engineering-level insight, but high-quality PSUs have nearly their full rated power available on +12V line. (Obviously not all the maximum powers are available continuously.)

bobkn said:

It means that there is a single +12V rail, rather than multiple ones.

The other lines (5V, 3.3V, etc.) are present.

Here are some of the specs from a Seasonic model:

View attachment 119921
I don't have engineering-level insight, but high-quality PSUs have nearly their full rated power available on +12V line. (Obviously not all the maximum powers are available continuously.)

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Interesting. I thought when you said 12V, it meant the other rails no longer exist but it appears the other rails do exist or else they wouldn't list the DC output for each rail since remember, I did say I didn't keep up with parts and stuff after 2009.

The +3.3V at 25A is 82.5W not 125W. The +5V is 125W but they leave it blank. The rails also add up to 1,221W for the output which is the maximum power. The specs also does not mention at what temperature will you get these specs. So while it does list 996W which is not continuous, they also do not tell you what the continuous rating is per rail which is the important part. It's similar to wattage on audio equipment, there is the RMS and then there is the peak power. All you know is the peak power and not the RMS rating. Similar to storage, there is the sustained rate and the burst rate. Only the sustained rate is reliable as the burst means it uses what's already in the cache.

Using a PC Power & Cooling 1200W PSU for example:


+3.3V @ 24A = 79.2W
+5V @ 30A = 150W
+12V @ 100A = 1200W
-12V @ 0.8A = 9.6W
+5VSB @ 4A = 20W

so let's see if their other ratings are accurate or not,
+5V (150W) + 3.3V (79.2W) = 229.2W and they list it less at 200W
Seems like everyone is listing only the +12V output as the wattage for the entire power supply
but their +12V can do a maximum of 115A which is 1,380W which 15s means for 15 seconds only.

So this is a example that it will deliver 100%, not nearly of the full rated power continuously and 115% if peaked. These are all at up to 50C in termperature.

They cost more for a reason as the power is also cleaner due to the power filtration which is also important not just wattage.

This is from the Seasonic PRIME PX ATX 3 (2024) 2200W

While this one does do 2200W continuously, the other specs are the ones one should be concerned about.

Electrical Features Operating Temperature 0 - 50 °C
MTBF @ 25 °C, excl. fan 100,000 hours

the MTBF is rated for 25C and not 50C which means the life is going to be shorter at temps above 25C
The 3.3V @ 25A is once again showing 125W when it's 82.5W in reality as each 1A = 3.3Watts.

Almighty1 said:

Interesting. I thought when you said 12V, it meant the other rails no longer exist since remember, I did say I didn't keep up with parts and stuff after 2009.

The +3.3V at 25A is 82.5W not 125W. The +5V is 125W but they leave it blank. The rails also add up to 1,221W for the output which is the maximum power. The specs also does not mention at what temperature will you get these specs. So while it does list 996W which is not continuous, they also do not tell you what the continuous rating is per rail which is the important part. It's similar to wattage on audio equipment, there is the RMS and then there is the peak power. All you know is the peak power and not the RMS rating.

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I have no idea what RMS might mean in the context of a PSU.

I also don't know what it might mean for audio equipment. Many makers of AVRs (audio video receivers) often list the power available on 1 or 2 channels, but not what you can get if multiple (say, 7) channels are run at the same level simultaneously. (Which rarely happens in real use.) It's usually much less than the 1 or 2 channel power.

Some audio gear can provide bursts of power by using capacitors. I recall some Heathkit amps for 50 years ago that allowed you to buy extra caps to allow longer transient power boosts.

I know what RMS means for AC power from the wall, though.

bobkn said:

I have no idea what RMS might mean in the context of a PSU.

I also don't know what it might mean for audio equipment. Many makers of AVRs (audio video receivers) often list the power available on 1 or 2 channels, but not what you can get if multiple (say, 7) channels are run at the same level simultaneously. (Which rarely happens in real use.) It's usually much less than the 1 or 2 channel power.

Some audio gear can provide bursts of power by using capacitors. I recall some Heathkit amps for 50 years ago that allowed you to buy extra caps to allow longer transient power boosts.

I know what RMS means for AC power from the wall, though.

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RMS = Continuous power and Peak is like the maximum that can be done.

I was just using an analogy that for audio, there is RMS (continuous) vs peak power output. For storage, there is the sustained rate (continuous) and then there is the burst speed.
For CPUs, there is the rated speed and then there is the peak speed.
Specs alone does not mean much unless they also show the output tolerage as in -+% of the rating and also the noise and ripple measurement for the output ratings and also what's part of the protection circuitry among many things. There is quantity and there is quality in that quantity which is not given based on reading specs alone as you really have to know what's inside like what brand of capacitors they use, if it's 80C or if it's 105C rated, etc. I know my PC Power & Cooling ATX 450 was not made by Seasonic but it is made by Win-Tact as this was 2002 or so when the Intel Pentium P4 started having the special connector and mines was basically the ones right before that connector was part of the same model power supply. It used Teapo capacitors and also Sanyo solid state capacitors.

This is what it used:
Mini Circuit Board
(c208) Teapo 10uF 50v 10/99
(c201) Sanyo 2.2/25 OS-CON Solid State Capacitor
(Extension Board of Mini Circuit Board) 4.7uF 50v 03/99
(c318) Teapo 68uF 25v 10/99
(c309) Teapo 1uF 50v 04/00
(c310) Teapo 1uF 50v 04/00
(c302) Teapo 10uF 50v 12/99
(u301) PCE-TUR 1uF 50v 2008
(c303) PCE-TUR 1uF 50v 2008

Main Circuit Board
(c3) Teapo 200v 1000uF (swollen) 01/00
(c4) Teapo 200v 1000uF (swollen) 01/00
(c12) Teapo 25v 47uF 09/98
(c13) Teapo 25v 100uF 06/00
(c14) Teapo 6.3v 1000uF 01/00
(c43) Teapo 6.3v 47uF 01/00
(c33) Teapo 25v 22uF 11/99
(c15) Teapo 6.3v 1000uF 01/00
(c36) Teapo 25v 100uF 03/00
(c20) Teapo 25v 100uF 01/00
(c19) Hermei 25v 1000uF no date stamp
(c21) Teapo 25v 100uF 01/00
(c40) Hermei 10v 4700uF 0436
(c39) Teapo 10v 6800uF (swollen & leaking) 09/04
(c35) Hermei 10v 4700uF (swollen) 0436
(Right of C35) Hermei 10v 4700uF 0436
(c23) Teapo 16v 4700uF 08/00
(c24) Teapo 16v 4700uF 08/00

This is what I replaced it with:
2 x 50v 10uF 6mmx13mm -> United Chemi-Con KY (Indonesia 41 Yk) 50v 10uF 5mmX11mm (D)

1 x 50v 4.7uF 6mmx13mm -> United Chemi-Con KY (Indonesia 41 bK) 50v 4.7uF 5mmx11mm (D)

1 x 25v 68uF 7mmx13mm -> Rubycon ZLH (Japan A1422) 25v 68uF 5mmx11mm (D)

4 x 50v 1uF 5mmx8mm -> Rubycon YXJ (Japan A1414) 50v 1uF 5mmX11mm (D)

2 x 200v 1000uF 25mmx52mm -> Panasonic TS-ED (Malaysia 1O10D) 200v 1000uF 25mmx45mm(M)

1 x 25v 47uF 6mmx12.5mm -> Panasonic FR (Malaysia 41IVGN) 25v 47uF 5mmX11mm (D)

4 x 25v 100uF 7mmx12mm -> United Chemi-Con KY (Indonesia 4 (k) 1 J) 25v 100uF 6.3mmx11mm (D)

2 x 6.3v 1000uF 9mmx16mm -> United Chemi-Con KY (Indonesia 4 (k) 3 Q) 10v 1000uF 8mmx20mm (D)

1 x 6.3v 47uF 6mmx8mm -> Nichicon PW (Malaysia B1216) 10v 47uF 5mmx11mm (D)

1 x 25v 22uF 6mmx13mm -> Panasonic FR (Malaysia 20IV0B) 50v 22uF 5mmx11mm (D)

1 x 25v 1000uF 11mmx21mm -> United Chemi-Con KY (Japan 3(T) 9 R) 25v 1000uF 10mmx30mm (D)

3 x 10v 4700uF 13mmx31mm -> United Chemi-Con KY (China 2(T) 0 V) 10v 4700uF 12.5mmx35mm (D)

1 x 10v 6800uF 17mmx37mm -> United Chemi-Con KY (Japan 3(T) 1b) 10v 6800uF 16mmx31.5mm (D)

2 x 16v 4700uF 14mmx41mm -> United Chemi-Con KYB (Japan 4 (2) 8E) 16v 4700uF 12.5mmx35mm (D)

which was 10 years ago and it's still working fine 24/7/365.

So even though many PSUs are made by Seasonic, depending on how much the companies are willing to pay, it could be better or worse than Seasonic's own product line as the companies can request certain things to be different.

As for AVRs, watts is only half the story. Compare 30Watts on something like Marantz or Harman-Kardon, you will find that 1 Watt on those two is equal to 10Watts on things like Sony, Sony ES, Pioneer for example because it's not just the wattage that matters but the current per watt. Actually if you get a quality amplifier like a Proceed AMP5 which is basically a baby Mark Levinson, you will notice that the wattage is on all the channels continuous at 8 Ohms and then the wattage doubles at 4 Ohms so I am not talking about burst either as the burst is the peak power. The AMP5 is also 125lbs and my laptop I am typing on now is on top of the box with one inside. So what I am saying is there are two ratings, one is continuous and the other is peak. The peak doesn't really matter as it's more like burst for a very short period of time. AMP5 doesn't seem to provide the peak rating but when you see the wattage double at 4Ohms, you already know it's high current as a lot of gear will not provide twice the wattage at 4Ohms.

In audio, the three that are most notorious with overrating their new models are Pioneer (Except Elite), Yamaha, and Sony. For example, the Yamaha 463 test by HT Magazine. This receiver is rated for 105wpc. On the bench, it only put out about 33wpc. Another example is the Pioneer 918 which is rated at 120wpc and only output 34wpc on the bench. In short, if HK says 50wpc, you're getting at least that amount into all channels.

Almighty1 said:

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In audio, the three that are most notorious with overrating their new models are Pioneer (Except Elite), Yamaha, and Sony. For example, the Yamaha 463 test by HT Magazine. This receiver is rated for 105wpc. On the bench, it only put out about 33wpc. Another example is the Pioneer 918 which is rated at 120wpc and only output 34wpc on the bench. In short, if HK says 50wpc, you're getting at least that amount into all channels.

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This is wandering off topic quite a bit, but you may be misleading some.

The Pioneer and Yamaha machine probably produce their specified power, but only into 1 or 2 channels at a time. (I didn't find the reviews that you mention online.) It's debatable as to how sleazy this might be.

As I said before, mass market audio manufacturers typically do not specify the minimum power if all channels are run at the same level simultaneously. It's usually much less than the one or two channel power.

Some of them don't like low impedance speakers, either.

I won't drag vacuum tubes into the discussion.

I am a wee bit late to the party, but I always use this calculator:


Just to compare, I did the calculations by hand on my two machines and this calculator was pretty darn close. It was less than 25 Watts difference on both machines that I fed into it.

Ghot said:

Be aware, they don't make power supplies like this any more.
This sucker is non-modular, and has a 10 year warranty.
I've been running it 24/7 for 15-16 years so far.
All the numbers are STILL right on the money.


View attachment 119811

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PC Power & Cooling never had a 10 year warranty.

"PC Power & Cooling, with a long-standing reputation as one of the leading high-performance computer power supply companies in the world, has established a new and improved warranty program for its two flagship models. The warranty for the award-winning Silencer Series, formerly sold with a 3-year commitment, will be stepped up to 5-years, while the warranty length for the maximum-performance Turbo-Cool Series will be extended from it's current 5-year commitment to a full 7-year warranty.

"As customers will often report that PC Power & Cooling PSUs continue to power their machines after more than a decade, we have decided to extend our warranties for both the Silencer and Turbo-Cool lines by 2-years, as an expression of our continued confidence in PC Power products and ongoing commitment to our customers," said PCP&C founder Doug Dodson."

Better source is PC Power & Cooling:

7 was the maximum and that's on the Turbo-Cool line made by Win-Tact which is what I have. It failed a few days before the 5 year mark so warranty basically had them replace the capacitors and the second time it failed which was 5 years later, I had to replace all the capacitors myself. This is running 24/7/365. The 5 year was extended to 7 years later. I actually ordered the Turbo-Cool 400ATX from PCP&C directly and got upgraded to a Turbo-Cool 450ATX instead but it was one expensive PSU compared to things like Corsair, Antec and all the other brands people buy.

bobkn said:

This is wandering off topic quite a bit, but you may be misleading some.

The Pioneer and Yamaha machine probably produce their specified power, but only into 1 or 2 channels at a time. (I didn't find the reviews that you mention online.) It's debatable as to how sleazy this might be.

As I said before, mass market audio manufacturers typically do not specify the minimum power if all channels are run at the same level simultaneously. It's usually much less than the one or two channel power.

Some of them don't like low impedance speakers, either.

I won't drag vacuum tubes into the discussion.

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It's not misleading since this is from people who actually know more about this. Basically what they advertise is not the real specs which is why it's misleading. This is talking about 2 channel stereo before multi-channels so it didn't deliver the rating in stereo 2 channels as the manufacturer lists in the specs. This was even the case in the 1990s and talking about stereo receivers, not multi-channel ones. If they can't even get the output with 2 channels, they wouldn't be able to do it with multi-channels either because receivers usually will require big power supplies to deliver the current.

Vacuum tubes are low wattage as well from what I recall. I'm just saying like your earlier comment, you can't look at it based on specs alone as everyone will usually print good looking specs but actual specs is another issue altogether which can only be found by either testing it yourself or from third party credible information. The reviews is something I found mentioned in a thread and might have long disappeared now depending when they were originally written.
And lots of this can be found on avsforum such as Does Sony says right about its "1000w" power... but regardless, the bottom line is what they claim and advertise for the specs is way above what it is in reality which is exactly what you said above which is why you can't rely 100% on what the spec sheets says for a power supply.

And this is interesting too. https://electronics.sony.com/audio/...sE-HTfEMa3hlmAzXWx7ffnia7dTFUoFDvQ30aoLIu9L8G - They don't even tell you what the power output is other than it's 13.2 channels.

And when you look at the manual found here:
on page 36, it specificallly says:
"STR-AZ7000ES With 8 Ω loads, both channels driven, from 20 Hz – 20 000 Hz; rated 140 W per channel minimum RMS power in stereo mode, with no more than 0.09% total harmonic distortion from 250 mW to rated output."

The misleading part which is what many have said is the 140WPC in stereo mode as it is usually way less.

And they do tell you the power in all channels:

Amplifier section1)2) STR-AZ7000ES
Rated Power Output at Stereo Mode (8 ohms, 20 Hz – 20 kHz, THD 0.09%): 140 W + 140 W Reference Power Output (8 ohms, 1 kHz, THD 0.9%) FRONT: 150 W + 150 W CENTER: 150 W SURROUND: 150 W + 150 W SURROUND BACK: 150 W + 150 W HEIGHT 1: 150 W + 150 W HEIGHT 2: 150 W + 150 W HEIGHT 3: 150 W + 150 W

So apparently, in multi-channel mode, all channels are 150W RMS including the front stereo channels. So it is actually 150W RMS for the front 2 channels instead of 140W RMS when in stereo mode. and remember this is the Sony ES line which is the same level as Pioneer Elite so obvious it's better than the standard Sony line. The wattage thing is discussed here too:

Almighty1 said:

(snip)

This is what it used:
Mini Circuit Board
(c208) Teapo 10uF 50v 10/99
(c201) Sanyo 2.2/25 OS-CON Solid State Capacitor

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(snip)

Takes TMI to a whole new level.

Almighty1 said:

(snip)

Vacuum tubes are low wattage as well from what I recall.

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(snip)

Depends. The famous Julius Futterman amps made 25W into 8 Ohms, if memory serves. (More into 16 Ohms. No output transformer.)

McIntosh will sell you a "300W" monoblock. McIntosh MC3500 Vacuum Tube Amplifier Mk II

Whether anyone makes an audio amp using transmitter tubes (which can do a lot more than 300W), I have no idea. In a business where some will sell you a cheater cord that is claimed to improve the sound (I'm not referring to noise pickup), nothing is too ridiculous to exist.

I think the whole point is how honest the specs are regardless what you are buying and what they are using to measure it so the same will apply to anything you buy as part of it is marketing. I mean it seems like PSU's have gotten so big in advertised wattage that it's hard to know how much one really needs as other than the video cards, it should be less as remember SSD's use less power than spindles and people no longer have dual floppy drives and other things.
I mean even that 2200W PSU, that needs 230VAC and not 120VAC which will not work for most in the US anyways. Maybe the best way to do it is just read reviews where they actually test the PSUs or something, hoping reviews actually exist for that make/model.

Atleast with a McIntosh, you will know what you are getting. Then there is this at $USD133,381.72 which is 260WPC RMS:

bobkn said:

(snip)

Takes TMI to a whole new level.

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It's not TMI as it's almost like judging a book by it's cover without even knowing what's inside. If you don't know what's inside where it counts, it's called being competent and performing due diligence. It is also from personal experience. Seasonic or any manufacturer can tell you that their PSU can take you to the moon which might or might not be true.

In a way... it sounds like Marketing (showing Higher Wattage - so you think you need and buy more expensive PSUs). On the other hand... maybe they don't trust the quality of the PSUs they sell or make - so maybe NewEgg (they do cover a multitude of brands) and Be-Quiet have a larger number of mediocre PSUs (saying this based on the wattaage calculator results from the OP - cause experience wise - didn't have any issues with this PSU, thos always went with +200W higher wattage than required "from the top of my head - no wattage calulator used" ) - so it's safer to go with higher Wattage.

Personally, so far - i never went wrong with Seasonic:

With any brand, it's really a YMMV just like what they said about cars. Don't buy the ones made on Friday or Monday as on friday, they are in a rush to go home for the weekend and on monday, they are returning back to work from the weekend. You can have 2 persons buying the exact same make/model and one will last forever and one will fail after a short bit of time. It's luck of the draw as the MTBF is only a average and not from actual usage. Similar to cars, European cars are better in performance but Japanese cars are better in reliability. The other issue is has anyone here actually had a Seasonic failed and how they handle the warranty which is also important as Seasonic is a chinese company in Guangdong, China and being Chinese myself, things are not of the highest quality either. People also say that this brand or that brand is rebadged Seasonic but it might or might not be the same exact product as the Seasonic branded product as the company can ask Seasonic to upgrade certain things and also downgrade certain things by using cheaper parts with the same specs to have the exact spec but how tight the tolerance is, is another matter altogether. As far as wattage is concerned, it's better to always have overhead when needed than to have it only meeting the requirements with no room to move when needed and you won't be pushing things to 100% capacity either. And ofcourse it depends also how often one changes PSU's as well so reliability for the longer term may not even be a factor.

As far as reviews go, what someone said elsewhere could be true too:
"Brand alone mean nothing, but the reputation and the history of the brand give a good starting point. As there are brands that do ship out good quality product to the reviewers and first batch of their product but then switch to inferior parts on sub-sequence batches while keeping the same model number of the product. In those cases, rely on good review alone means absolutely nothing."