luckybob wrote:

^^^ basically true.

The majority of NEW power supply designs, they are designed to make +12. THEN they put in a dc/dc converter for the 5v and 3.3v. This means you can basically load it however you want to. A Pentium 3 wont stress a quality psu to any significant degree. A P4 will, but most of them are designed for high 12v loads.

moral of the story; get a quality unit, and forget about it.

Wait, I missed this one post on the first place.

So does it mean that it doesn't matter if your combined 3.3V+ and 5.5V+ power consumption exceeds that of the PSU? Let say, your PSU's combined power of the 3.3V+ and 5.5V+ is only 150W, yet you can draw, say, 180W on the combined 3.3V+ and 5.5V+ as long as your total power draw (including 12V+ power draw) doesn't exceed the total power capacity of your PSU, because the 3.3V+ and 5.5V+ comes from the 12V+ anyway.

I have forgotten a lot about basic electronics, but could someone tell me if I'm wrong?

Nope. You are limited by the capacity of the DC/DC converter. It is not infinite - and 5V rails on modern PSUs don't have to be very powerful, so that converter will probably reach its limits way before the total power capacity of the PSU. I'd trust the capacity it claims to be able to deliver to be accurate (if the PSU is from a trustworthy brand) and match what the buck down converter can actually deliver within spec.

Kreshna Aryaguna Nurzaman wrote:

... does it mean that it doesn't matter if your combined 3.3V+ and 5.5V+ power consumption exceeds that of the PSU? Let say, your PSU's combined power of the 3.3V+ and 5.5V+ is only 150W, yet you can draw, say, 180W on the combined 3.3V+ and 5.5V+ as long as your total power draw (including 12V+ power draw) doesn't exceed the total power capacity of your PSU, because the 3.3V+ and 5.5V+ comes from the 12V+ anyway ...

No, it's not that easy unfortunately.

Luckybob is referring to modern DC-DC PSUs, in these the main transformer only generates +12V, then DC-DC converters step down voltage for the minor rails (+5V & +3.3V) from the main +12V rail.

These modern DC-DC PSUs (together with independently regulated or 'Indy' PSUs) are basically inmune to crossload voltage drop (like +5V voltage dropping below ATX spec when +5V load is large and +12V load is small, like in retrocomps), unlike traditional cheaper group-regulated PSUs.

Explanation of the three types of voltage regulation: Group-regulation, Indy-regulation, and DC-DC.

However modern DC-DC PSU's are still subjected to amperage limits on +5V, and combined wattage limits for +5V & +3.3V.

^ This Seasonic G-550 is a DC-DC design, and yet it's limited to 20A on +5V and 100W max combined +5V & +3.3V.

If we exceed these limits we'll be overloading the DC-DC converters and other components, and mileage may vary from 'no problem, can cope' to 'my PSU is burning!', there are no guarantees.

Is reading the 5V voltage the only way to understand if the psu is stressing and overloading or you must calculate every power components?

With the multimeter the VS650 with Athlon 900 / 512 PC133 / Voodoo3 2000 / 4 PCI / 1HD / 1 DRIVE is at 12,01V and 4,93V at the drive connector. Bios reading was a bit better..

386SX wrote:

Is reading the 5V voltage the only way to understand if the psu is stressing and overloading or you must calculate every power components?

To really KNOW how much the PSU is really drawing, we need amperage meters.

A Kill-a-Watt is an amperage meter that reads total system draw from the wall. It doesn't tell us how much each component, or each rail, is drawing, only total computer draw.

Barring hardcore tinkering (or a very sophisticated PSU), the average user can't really know how much the +5V rail alone is really drawing.

A multimeter can read voltages, and thus can tell us if the +5V rail is dropping below ATX spec (4.75 to 5.25V) when a group-regulated PSU is unable to regulate voltage adequately due to heavily unbalanced loads (like modern group-regulated PSUs dealing with old +5V heavy / +12V light retrocomps).

386SX wrote:

With the multimeter the VS650 with Athlon 900 / 512 PC133 / Voodoo3 2000 / 4 PCI / 1HD / 1 DRIVE is at 12,01V and 4,93V at the drive connector. Bios reading was a bit better..

^ Good, that's very little deviation. If that holds true from idle to full steam, then you should be fine.

Trust only the multimeter (provided it's a half-decent one, that is). BIOS voltages are not that reliable, and software voltage readings (like HWmonitor, SpeedFan, etc.) are completely unreliable.

TELVM wrote:

To really KNOW how much the PSU is really drawing, we need amperage meters. […]
Show full quote

386SX wrote:

Is reading the 5V voltage the only way to understand if the psu is stressing and overloading or you must calculate every power components?

To really KNOW how much the PSU is really drawing, we need amperage meters.

A Kill-a-Watt is an amperage meter that reads total system draw from the wall. It doesn't tell us how much each component, or each rail, is drawing, only total computer draw.

Barring hardcore tinkering (or a very sophisticated PSU), the average user can't really know how much the +5V rail alone is really drawing.

A multimeter can read voltages, and thus can tell us if the +5V rail is dropping below ATX spec (4.75 to 5.25V) when a group-regulated PSU is unable to regulate voltage adequately due to heavily unbalanced loads (like modern group-regulated PSUs dealing with old +5V heavy / +12V light retrocomps).

386SX wrote:

With the multimeter the VS650 with Athlon 900 / 512 PC133 / Voodoo3 2000 / 4 PCI / 1HD / 1 DRIVE is at 12,01V and 4,93V at the drive connector. Bios reading was a bit better..

^ Good, that's very little deviation. If that holds true from idle to full steam, then you should be fine.

Trust only the multimeter (provided it's a half-decent one, that is). BIOS voltages are not that reliable, and software voltage readings (like HWmonitor, SpeedFan, etc.) are completely unreliable.

Thanx!
I switched to a Duron 800 from the Athlon 900 and reading again voltages. Now it's read 11,98V and 4,96V. I thought the Athlon was lowering more but it seems it doesnt make much difference. I suspect the Voodoo3 is asking a lot.

386SX wrote:

... 12,01V and 4,93V ... ... 11,98V and 4,96V ...

^ That's very little deviation!

386SX wrote:

... I suspect the Voodoo3 is asking a lot.

What makes you think so?

TELVM wrote:

^ That's very little deviation! http://smileys.on-my-web.com/repository/Respect/respect-048.gif […]
Show full quote

386SX wrote:

... 12,01V and 4,93V ... ... 11,98V and 4,96V ...

^ That's very little deviation!

386SX wrote:

... I suspect the Voodoo3 is asking a lot.

What makes you think so?

I can imagine not much difference between a Athlon and Duron at almost same freq/voltage. So of the other components the psu will be working hardly on the 5V rail I can only imagine the V3 that seems to be quiet power requiring (for its time). Considering generated heat I mean.

Nah, from what I read around the web the Voodoo 3 2000 may draw as little as only 10W. Doesn't even need additional power connector.

Your Athlon Classic system is just a very light burden for the VS650, she's half-asleep while powering it. 😀

I bet the PSU's rear grill is stone cold at all times.

TELVM wrote:

Nah, from what I read around the web the Voodoo 3 2000 may draw as little as only 10W. Doesn't even need additional power connector.

Your Athlon Classic system is just a very light burden for the VS650, she's half-asleep while powering it. 😀

I bet the PSU's rear grill is stone cold at all times.

Yes it's really cold the air from there. But I was thinking if it's cold cause the 12V rails is almost unused while the 5V rail being used or not would not make much difference in modern generated psu heat.
But the Athlon Thunderbird 1400 ask something similar to a Barton 3000+... I've seen some new cheap psu fail with just the cpu a cheap gpu and a drive...

Your system must be drawing about 100~150W AC from the wall at full load. That's a small fraction of the VS650 rating, relatively little heat is generated inside the PSU. And the 120mm fan (which probably spins fast to give the Jun Fus some life expectancy) dispatches the heat out easily.

386SX wrote:

... I've seen some new cheap psu fail with just the cpu a cheap gpu and a drive...

That's the difference between a cheap overrated fire-hazard gutless wonder and a passably decent PSU.

TELVM wrote:

Your system must be drawing about 100~150W AC from the wall at full load. That's a small fraction of the VS650 rating, relatively little heat is generated inside the PSU. And the 120mm fan (which probably spins fast to give the Jun Fus some life expectancy) dispatches the heat out easily.

386SX wrote:

... I've seen some new cheap psu fail with just the cpu a cheap gpu and a drive...

That's the difference between a cheap overrated fire-hazard gutless wonder and a passably decent PSU.

Next time I buy another psu I will buy the best that last as much as possible. No matter if it's for a K6-2 system. 😁

You don't need to spend $400 on a Corsair AX1500i to get a quite decent PSU. 🤣

As an example of same horsepower than VS650, the Antec VPF650 (known as Earthwatts EA-650 GREEN in USA) is made by Delta and sports DC-DC, jap caps, and also a 20A +5V rail.

Here around the VPF650 costs ~72€, vs ~58€ for the VS650.

Thanks, I am reading the review. Any other already reviewed up to 30 on 5V and not too much on the 12V rail you like that doens't cost too much? Less total wattage and more quality?
I like a lot this one reviewed at hardwaresecrets.com the Seasonic X Series KM3 650W.. a bit expensive for me 🙁

TELVM wrote:

As an example of same horsepower than VS650, the Antec VPF650 (known as Earthwatts EA-650 GREEN in USA) is made by Delta and sports DC-DC, jap caps, and also a 20A +5V rail.

I would be carefull with that.
Antec has yet again changed the product without changing the model number.
The current Antec EA-650 Green may not be Delta and has a whopping 95W on 3.3v+5v combined.

It looks like they changed whole model line this way.
The old "green" lineup was EA-380D, EA-430D, EA-500D, EA-650.
The new "green" lineup is EA-350, EA-450, EA-550, EA-650.
Every one of the new ones only has 95W on 3.3v+5v combined.
(Thus if your concern is 3.3v+5v watts, it doesn't matter which one you use.)

{Note: The original EA-650 was Delta but did not get the "D" designation because there was no pre-Delta version of the 650w.)

So, if you want a "good" "Delta" Antec Earthwatts you will be buying NOS or used.
They may have done the same with that "VPF" on your side of the pond.
.
(From current Amazon Ad)

Current EA-650 Green

Older EA-650 Greens

The "Pre-Green" EA-650 is the only Eartwatts 650w I personally used (160W 3.3v+5v) but I did not like them.
Nothing ever broke but they have an odd "fan-kick" when you turn them off. They go off - then the fan kicks.

.
The 500W Earthwatts (all versions) have been problem free for me and I've used a lot of them (40?) in basic office machines.
Same with the 380W and 430W but they will need recapped. (And I've only used a few for special low power apps.)
I buy them used and out of all the Earthwatts 380-430-500 watt I've bought there was only one dud. I never buy them "untested" though.
They are not suitable for a +5v heavy retro gaming machine so I didn't bring them up earlier. Sort of OT.
.

With what I spent lately on cheap and bad psu, well if I find the Antec/Delta ok if not I understand also the Seasonic X serie KM3 650W would be a safe and long term choice, isn't it?

386SX wrote:

With what I spent lately on cheap and bad psu, well if I find the Antec/Delta ok if not I understand also the Seasonic X serie KM3 650W would be a safe and long term choice, isn't it?

Looked at jonnyguru and Hardware Secrets reviews. I haven't seen one personally.
The Seasonic looks like an excellent PSU if it will work for your application.
(Sorry, this thread is getting long and I forgot what you are working on.)
With 125w 3.3v+5v and leaving 10% for a safety margin (to PSU maxed out) you should be fine with up to a 112.5w 3.3v+5v load.

But the plan of buying a new over-kill high makes no sense to me.
With that plan this (checking Newegg to me) that model currently costs $116 after shipping.
If cost is concern that is not a good choice. The alternatives would cost 25%-50% as much.

As example:
I just bought one of these for $20 (shipped).
I couldn't help myself.
This one is pretty blue metal flake and I've been wanting to look inside some old Enermax anyway.

It's warranted as working but I'm assuming it will need recapped.
[Beware that Enermax is like Antec in that the same model number can have different ratings.]
Even if I don't have the caps and have to order the caps are going to cost UNDER $20 (with shipping). Probably closer to $10.
[If you make a habit of buying a few surplus so you already have the caps then it can be under $5 when you don't have to order.]

So $40 for PSU+Caps vs $116 for the Seasonic. :: $116 - $40 = $76.

Even if I was starting with no soldering gear at all $76 would easily cover everything essential to rebuilding PSUs...
... and I would save at least $76 on every PSU I did after that.
To look at it another way, 3+ PSUs for the price of 1.
Even if you are unlucky and get 1/3 duds (as used) you are ahead.
I am picky buying used and my "dud-rate" buying used is about the same as buying brand new.

You only need basic soldering gear and basic soldering skills to do PSUs. (Motherboards is different.)
The only part that is actually tough for PSUs is learning what caps to get and finding them.
.
If you replace caps with caps with the same uF and the same or slightly better ESR then you don't need things like O'scopes.
(You are upgrading quality, not changing specifications.)
While good to have (and recommended) an ESR meter is optional if you blanketly replace all bad brands with brand new (vs old stock) caps.
(No need to check old ones if you are tossing all of them anyway.)
(Fresh stock Jap caps caps are very rarely bad. I don't think I've ever even seen one. - Old stock is different.)
.

PCBONEZ wrote:

Looked at jonnyguru and Hardware Secrets reviews. I haven't seen one personally. The Seasonic looks like an excellent PSU if it […]
Show full quote

Looked at jonnyguru and Hardware Secrets reviews. I haven't seen one personally.
The Seasonic looks like an excellent PSU if it will work for your application.
(Sorry, this thread is getting long and I forgot what you are working on.)
With 125w 3.3v+5v and leaving 10% for a safety margin (to PSU maxed out) you should be fine with up to a 112.5w 3.3v+5v load.

Seasonic X-650 KM3 650W.jpg

But the plan of buying a new over-kill high makes no sense to me.
With that plan this (checking Newegg to me) that model currently costs $116 after shipping.
If cost is concern that is not a good choice. The alternatives would cost 25%-50% as much.

As example:
I just bought one of these for $20 (shipped).
I couldn't help myself.
This one is pretty blue metal flake and I've been wanting to look inside some old Enermax anyway.

M_EG465P-VE.jpg

It's warranted as working but I'm assuming it will need recapped.
[Beware that Enermax is like Antec in that the same model number can have different ratings.]
Even if I don't have the caps and have to order the caps are going to cost UNDER $20 (with shipping). Probably closer to $10.
[If you make a habit of buying a few surplus so you already have the caps then it can be under $5 when you don't have to order.]

So $40 for PSU+Caps vs $116 for the Seasonic. :: $116 - $40 = $76.

Even if I was starting with no soldering gear at all $76 would easily cover everything essential to rebuilding PSUs...
... and I would save at least $76 on every PSU I did after that.
To look at it another way, 3+ PSUs for the price of 1.
Even if you are unlucky and get 1/3 duds (as used) you are ahead.
I am picky buying used and my "dud-rate" buying used is about the same as buying brand new.

You only need basic soldering gear and basic soldering skills to do PSUs. (Motherboards is different.)
The only part that is actually tough for PSUs is learning what caps to get and finding them.
.
If you replace caps with caps with the same uF and the same or slightly better ESR then you don't need things like O'scopes.
(You are upgrading quality, not changing specifications.)
While good to have (and recommended) an ESR meter is optional if you blanketly replace all bad brands with brand new (vs old stock) caps.
(No need to check old ones if you are tossing all of them anyway.)
(Fresh stock Jap caps caps are very rarely bad. I don't think I've ever even seen one. - Old stock is different.)
.

Well I would like to have one good and safe psu I can use for any retro machines up to the Barton/Athlon64 and also eventually for a new not-expensive modern pc. But more than recapping the problem seems to find the exact compatible high quality replacement cause sometimes I see few indications on the caps to replace. Today I opened an unbranded 400W old P4 compatible psu that seems quiet good on weight and components inside but when I looked at the back of the pcb soldering is just awful.. recapping would not solve it..

Is Hercules a good retro PSU brand?

PCBONEZ wrote:

I would be carefull with that.
Antec has yet again changed the product without changing the model number.

Ouch, I wasn't aware of that. Here around the VPF650 Bronze still has 20A on +5V.

Kreshna Aryaguna Nurzaman wrote:

Is Hercules a good retro PSU brand?

I'll just leave this here: Death of a Gutless Wonder III: The Labors of Hercules