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#11
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motherboard 5v
On Mon, 3 Jun 2019 16:49:28 -0500, VanguardLH wrote:
I don't need an economics expert. I only asked about voltage. Oh, so quality of the PSU, it voltage regulation, ripple, accuracy of your multimeter So now you doubt my multimeter. I don't need Usenet snobs either. |
#12
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motherboard 5v
On Mon, 03 Jun 2019 16:55:39 +0000, T. Ment
wrote: I spent $20 on the power supply. $6 on the motherboard. No more money in the budget. Does anybody know anything, except "replace the power supply"? You're my kind of guy. I have a couple such power supplies, $20 sale items, in their boxes for backups: One's actually a decent EVGA, the other a no-namer. It's OK sometimes. Sometimes, though, if you want to play then you have to pay. |
#13
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motherboard 5v
On Mon, 03 Jun 2019 18:31:21 -0400, Flasherly
wrote: It's OK sometimes. Sometimes, though, if you want to play then you have to pay. At a simplest base you're acquainted, somewhat conversant, at least to know what's to be expected of your MB. Simply, then, that it works well enough for you to go poking around, on the side, with a multimeter, for fun things to do. Say, that were to change, not in the most obvious manner, nor necessarily an insidious aspect. But, as it were, your computer begins to display anomalistic annoyances. Here and there the happenstance or quirks not, decidedly, characteristic of either possibly correctly configured software or potentially hardware which is in within its intended specifications. This is the juncture where that spare power supply replacement can be nothing short of a required indicative for modular troubleshooting. And I'm going on personal experience. Those contingencies above, taken from when I acquired a MB and a subsequent course of time to evince behavior of a troublesome note, I have had on more than one occasion a successful response through replacement of a PS unit. Can't say more, though, about my hell'va DMM modeled after FLUKE from a $20 Singapore sales bin. Nor have I yet experienced adverse affects on hard drives from a faulty PS unit. It never quite went that far. A spare PSU is pretty much a standard go-to at the first hint of operational anomalies. And that is, besides, one of the simplest procedures provided to follow: Simply to replace it when in question and for comparative purposes. You said it's only $20 and presumably you've only that. My advice is to find another, say even if at $6 used while in known working order. I personally put a PS high up there in a modularity swapping order. Of course it becomes ultimately reducible to all modularity, to at least build or keep components to a computer functional. Saying you don't like to spend (a lot) money is fine. What that ultimately means is you're going to need to know where, precisely, to point that least amount of money, possibly, for the biggest bang on your buck for equipment that fulfills your expectations. Modularity has now been covered. What's next in a course on computers is a crux of redundancy or backing-up your butt for that safe landing. A PS, as I said, is well within contingencies qualifying for that aspect. Get to them ahead of time is how it's done. Get your spare PS, or whatever else, all on your good money on your good time on your best sale price. You do not want to buy when it breaks at the last minute, where you're left scrambling on "their" good time at "their: good mercy for a price you need then and there to pay. (Marketing 101: Perceived demand is only a matter of references.) |
#14
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motherboard 5v
On 6/3/2019 3:28 PM, VanguardLH wrote:
T. Ment wrote: On Mon, 03 Jun 2019 17:00:42 +0100 (BST), rp wrote: Replace the power supply. It's a $20 special. I don't care about perfection. That is way too cheap for a decent power supply. When I do a build, most of the PSUs that I end up looking at are $80 at a minimum but usually spend a lot more. However, I don't know what you got for capacity (VA or watts) for your PSU, or its efficiency (less efficient = more heat = more thermal stress = less capacity to internal components since the A/C outlet isn't changing its voltage). Figure on losing 5% capacity each year with a decent PSU. That's why I buy PSUs that are much higher in capacity than the load they will initially need to handle. For a 400W load, I'd get a 750W PSU because in 8 years (what I like to build for longevity) the PSU will still be more than enough at 66% of its initial capacity. The 5% is a rough estimate of capacity reduction, but PSUs do wane over time. Cheapies die off much quicker. The PSU supplies the life blood to the computer. If you do the build, you are the hematologist for the computer. How old is your $20 PSU? Was it a pre-built computer or did you do your own build? The PSUs that come in pre-builts are often minimal for the standard configuration by the model (with the same PSU used within a family of models). They don't overbuild since they're maximizing their profit margin. The 5v disk connector may well come from another regulator. At the very least measure the 5v at the motherboard multiconector from the psu. I won't buy another power supply if this one gets me by. My question is, what tolerance is safe. 4.75V is the minimum. Less voltage means supplying more current to handle the same load, and more current puts more thermal stress on the supply components. I'm curious as to why you say less voltage means supplying more current. Doesn't that violate Ohm's law? I = V / R If V = 5.00 Volts and the load (resistance) R = say 10 Ohms then the current I = 0.500 Amps. If V = 4.75 Volts and the same load then I = 0.475 Amps. Or is there some kind of perverse circuitry in computer power supplies that make them work differently? Charlie snip |
#15
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motherboard 5v
On Mon, 03 Jun 2019 20:29:07 -0400, Flasherly wrote:
Get your spare PS, or whatever else, all on your good money on your good time on your best sale price. My spare PS has a bad 16v 3300uf capacitor. I have a replacement part, but it's waiting for a day with nothing better to do. Paul said 5v minimum spec is 4.75v. But there must be some wiggle room outside the spec. The question is, how much? That's all I want to know. |
#16
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motherboard 5v
On Tue, 04 Jun 2019 01:49:23 +0000, T. Ment
wrote: The question is, how much? That's all I want to know. You cannot until it's more than suspect, than a 4.75V proposition, and a replacement (or your spare PS and a capacitor is restored), where for troubleshooting purposes, that is, a PS swap-out solves or changes a problematic or hypothetical equation. As I said, I keep the spare power supplies, and they're there for anything out of the ordinary matters I cannot, otherwise, account for other than a likelihood of an effectively new power supply. It has admittedly been awhile since I've proved to myself that logic. Also, awhile would entail entirely switching my acquisition of MBs exclusively to Gigabyte. Only that before then I'd several times encountered issues, with other brands, where a quick-&-jiffy swapover to a new PS solved them. Whether that's what you indeed do want to know, I cannot say can be conclusively stated from more than an empirical point of view. How long and how much are vagaries to assess assurances, like brandname reputability, MeanTime Between Failures, electronic design principles and theoreticians, and a physics to limitations and applied materials, their methodology and implementation over Quality Control given its measures and ratings Figure it this way, there are satellites that have been transmitting for going on decades taken to cross our solar system. So it can't be all that bad if your PS is more or less destined to a measure of Standard Deviation, to statistically fail either tomorrow or with greater certainty ensuing, whereupon a credible limit of 1/20th a voltage specification, at 5V, is not, minimally, present. Or, that satellite may be long gone and out of reception range before you'll notice anything characteristically different occurs, about your computer, from overall expectations of familiarity, which subsequently in turn can be consequent to an alteration produced by a PS replacement. |
#17
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motherboard 5v
Charlie wrote:
On 6/3/2019 3:28 PM, VanguardLH wrote: T. Ment wrote: On Mon, 03 Jun 2019 17:00:42 +0100 (BST), rp wrote: Replace the power supply. It's a $20 special. I don't care about perfection. That is way too cheap for a decent power supply. When I do a build, most of the PSUs that I end up looking at are $80 at a minimum but usually spend a lot more. However, I don't know what you got for capacity (VA or watts) for your PSU, or its efficiency (less efficient = more heat = more thermal stress = less capacity to internal components since the A/C outlet isn't changing its voltage). Figure on losing 5% capacity each year with a decent PSU. That's why I buy PSUs that are much higher in capacity than the load they will initially need to handle. For a 400W load, I'd get a 750W PSU because in 8 years (what I like to build for longevity) the PSU will still be more than enough at 66% of its initial capacity. The 5% is a rough estimate of capacity reduction, but PSUs do wane over time. Cheapies die off much quicker. The PSU supplies the life blood to the computer. If you do the build, you are the hematologist for the computer. How old is your $20 PSU? Was it a pre-built computer or did you do your own build? The PSUs that come in pre-builts are often minimal for the standard configuration by the model (with the same PSU used within a family of models). They don't overbuild since they're maximizing their profit margin. The 5v disk connector may well come from another regulator. At the very least measure the 5v at the motherboard multiconector from the psu. I won't buy another power supply if this one gets me by. My question is, what tolerance is safe. 4.75V is the minimum. Less voltage means supplying more current to handle the same load, and more current puts more thermal stress on the supply components. I'm curious as to why you say less voltage means supplying more current. Doesn't that violate Ohm's law? I = V / R If V = 5.00 Volts and the load (resistance) R = say 10 Ohms then the current I = 0.500 Amps. If V = 4.75 Volts and the same load then I = 0.475 Amps. Or is there some kind of perverse circuitry in computer power supplies that make them work differently? Charlie In the engineering profession, as time passes and you become "seasoned", you begin to realize there are certain topics you simply "don't wade into". There are things you don't "shoot from the hip". In logic design, the trap there, is jotting down a logic table on a table napkin, and selecting an AND/NAND/OR/NOR/XOR gate which you think corresponds to the table. 9 times out of 10, you'll get it wrong when you do that. Stick to your regular symbolic methods! So when someone tries to trick you, by making a logic table on a napkin, instead say "that's nice" and walk away :-) It's not that you don't like a challenge. It's that this challenge is intended to trick you into making an unnecessary mistake. The same happens with power calcs and statements about power. And by you writing up your statement like that, you sucked me into your vortex and tried to trick me! Good work :-) This is the third time I've had to write this answer. Again, good work! You tricked me. ******* The OPs electrical load consists of two parts. This is one of the boards, where the four +5V wires on the 20 pin connector, carry the power used by the processor. The VCore circuit, an SMPS, converts the power from 5V, to say, 1.5V. +5V --------+------------------+ 5V @ 13A +--------+ 1.5V @ 43.3A | | | | (regular ccts, +--- Vcore -----+ Athlon Ohms law is SMPS CPU (65W) close...) +--- (Constant --+ | | | power) | | GND --------+------------------+ +--------+ On an SMPS, the SMPS runs at constant power. It's a closed loop feedback system. It wants to run my mythical 1.5V processor at a constant 1.5V. And since I'm running 7ZIP compressor right now, my CPU is railed and drawing 43.3A. OK, now assume the rail voltage on the inlet side, drops to 4.75V. The SMPS still needs to make 65W for my processor. Using closed loop feedback, the inlet current *increases*. (And this is why some SMPS are equipped with UVLO or Undervoltage Lockout, so that if the voltage drops too low, something won't burn on the inlet side.) 65W ------ = 13.68A 4.75V +4.75V --------+------------------+ 4.75V @ 13.68A +--------+ 1.5V @ 43.3A | | | | (regular ccts, +--- Vcore -----+ Athlon Ohms law is SMPS CPU (65W) close...) +--- (Constant --+ | | | power) | | GND --------+------------------+ +--------+ So now we notice there's an item in the circuit, which doesn't follow Ohms law. And at close to 14 amps, it's a *major* part of the circuit in this case. The Ohms law part of the circuit, is well less than 14 amps. And I was this close to pushing the button on the other two versions of this post, and falling into the same trap I was going to warn you about. Again, good work :-) The above isn't a complete workup of the circuit. It's intended to illustrate the principle of "traps" in engineering. I've seen a couple of people nearly ruined by stuff like this. One guy, filled a lab with smoke one day and forced an evaluation... because he was so sure he was right... And that's the only time ever, that anyone did something stupid enough to cause an evacuation. If you have a device in hand, it's much better to just *measure* it, than dreamily attempt to analyze it with a half dozen table napkins. Paul (dammit!) |
#18
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motherboard 5v
T. Ment wrote:
On Mon, 03 Jun 2019 20:29:07 -0400, Flasherly wrote: Get your spare PS, or whatever else, all on your good money on your good time on your best sale price. My spare PS has a bad 16v 3300uf capacitor. I have a replacement part, but it's waiting for a day with nothing better to do. Paul said 5v minimum spec is 4.75v. But there must be some wiggle room outside the spec. The question is, how much? That's all I want to know. That's the spec. 5%. That's all the margin you're allowed. It's in all three of the ATX specs. Now, pull a TTL datasheet. What is the spec in there ? It's 5%. (Page 2, "Recommended Operating Conditions") I realize this is an old part, and this is purely to illustrate the situation we might fall into. https://www.futurlec.com/Datasheet/74ls/74LS02.pdf Design works with specs. There's a source and a sink for that spec. Notice in this case, we've got no margin for distribution loss. So what we can conclude from this, is the circuit actually runs with less than 4.75V. It will probably run down to around 3.6V or so. However, you don't want "things that cannot afford to make mistakes", running at 3.6V! It's OK to say they run down to 3.6V, as part of a bar bet. We had something in the lab one day, with a feedthru problem. Two modules (boxes full of logic chips), one had power, the other lost power, and there was so much leakage through some logic signals, that the second unpowered module "siphoned" power out of the other unit, and its logic was still running! Needless to say, we were shocked, and needed to go to the nearest bar for a drink :-) (Or something) Now, on good power supplies, the typical variability is 3%. But that's not how specsmanship works. I hope you can see that something is a bit broken in this picture, in terms of conservative design. I'm still not concerned. But I'm also not that happy. There are some brands of ATX supplies, that push crossload right to the spec limit on purpose, like evil school boys. And they really should not do that. Paul |
#19
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motherboard 5v
On Tue, 04 Jun 2019 01:24:16 -0400, Paul wrote:
There are some brands of ATX supplies, that push crossload right to the spec limit on purpose, like evil school boys. I must have the evil school boy type. At $20 I can live with that. All my computers are toys anyway. |
#20
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motherboard 5v
On 6/4/2019 1:10 AM, Paul wrote:
Charlie wrote: On 6/3/2019 3:28 PM, VanguardLH wrote: T. Ment wrote: On Mon, 03 Jun 2019 17:00:42 +0100 (BST), rp wrote: Replace the power supply. It's a $20 special. I don't care about perfection. That is way too cheap for a decent power supply.Â* When I do a build, most of the PSUs that I end up looking at are $80 at a minimum but usually spend a lot more.Â* However, I don't know what you got for capacity (VA or watts) for your PSU, or its efficiency (less efficient = more heat = more thermal stress = less capacity to internal components since the A/C outlet isn't changing its voltage). Figure on losing 5% capacity each year with a decent PSU.Â* That's why I buy PSUs that are much higher in capacity than the load they will initially need to handle.Â* For a 400W load, I'd get a 750W PSU because in 8 years (what I like to build for longevity) the PSU will still be more than enough at 66% of its initial capacity.Â* The 5% is a rough estimate of capacity reduction, but PSUs do wane over time.Â* Cheapies die off much quicker.Â* The PSU supplies the life blood to the computer. If you do the build, you are the hematologist for the computer. How old is your $20 PSU? Was it a pre-built computer or did you do your own build?Â* The PSUs that come in pre-builts are often minimal for the standard configuration by the model (with the same PSU used within a family of models).Â* They don't overbuild since they're maximizing their profit margin. The 5v disk connector may well come from another regulator. At the very least measure the 5v at the motherboard multiconector from the psu. I won't buy another power supply if this one gets me by. My question is, what tolerance is safe. 4.75V is the minimum.Â* Less voltage means supplying more current to handle the same load, and more current puts more thermal stress on the supply components. I'm curious as to why you say less voltage means supplying more current. Â*Doesn't that violate Ohm's law? I = V / R If V = 5.00 Volts and the load (resistance) R = say 10 Ohms then the current I = 0.500 Amps. If V = 4.75 Volts and the same load then I = 0.475 Amps. Or is there some kind of perverse circuitry in computer power supplies that make them work differently? Charlie In the engineering profession, as time passes and you become "seasoned", you begin to realize there are certain topics you simply "don't wade into". There are things you don't "shoot from the hip". In logic design, the trap there, is jotting down a logic table on a table napkin, and selecting an AND/NAND/OR/NOR/XOR gate which you think corresponds to the table. 9 times out of 10, you'll get it wrong when you do that. Stick to your regular symbolic methods! So when someone tries to trick you, by making a logic table on a napkin, instead say "that's nice" and walk away :-) It's not that you don't like a challenge. It's that this challenge is intended to trick you into making an unnecessary mistake. The same happens with power calcs and statements about power. And by you writing up your statement like that, you sucked me into your vortex and tried to trick me! Good work :-) LOL This is the third time I've had to write this answer. Again, good work! You tricked me. At least I'm good for something. ;-) Seriously, my intent was not to trick you or VanguardLH. I truly wanted to learn. ******* The OPs electrical load consists of two parts. This is one of the boards, where the four +5V wires on the 20 pin connector, carry the power used by the processor. The VCore circuit, an SMPS, converts the power from 5V, to say, 1.5V. Â*Â* +5V --------+------------------+ 5V @ 13AÂ*Â*Â*Â*Â*Â* +--------+ 1.5V @ 43.3A Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â* | Â*Â*Â*Â*Â*Â*Â*Â*Â* (regular ccts,Â*Â*Â*Â*Â*Â*Â*Â*Â* +--- VcoreÂ* -----+Â*Â*Â*Â*Â*Â* Athlon Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Ohms law isÂ*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* SMPSÂ*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* CPU (65W) Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* close...)Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* +--- (Constant --+Â*Â*Â*Â*Â*Â*Â* | Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â* power)Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â* | Â*Â* GND --------+------------------+Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* +--------+ On an SMPS, the SMPS runs at constant power. It's a closed loop feedback system. It wants to run my mythical 1.5V processor at a constant 1.5V. And since I'm running 7ZIP compressor right now, my CPU is railed and drawing 43.3A. Ah! The perverse circuit I was alluding to (only it isn't in the computer power supply but downstream of it). OK, now assume the rail voltage on the inlet side, drops to 4.75V. The SMPS still needs to make 65W for my processor. Using closed loop feedback, the inlet current *increases*. (And this is why some SMPS are equipped with UVLO or Undervoltage Lockout, so that if the voltage drops too low, something won't burn on the inlet side.) Â*Â*Â* 65W Â* ------ = 13.68A Â*Â* 4.75V +4.75V --------+------------------+ 4.75V @ 13.68A +--------+ 1.5V @ 43.3A Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â* | Â*Â*Â*Â*Â*Â*Â*Â*Â* (regular ccts,Â*Â*Â*Â*Â*Â*Â*Â*Â* +--- VcoreÂ* -----+Â*Â*Â*Â*Â* Athlon Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Ohms law isÂ*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* SMPSÂ*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* CPU (65W) Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* close...)Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* +--- (Constant --+Â*Â*Â*Â*Â*Â*Â* | Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* |Â*Â*Â*Â* power)Â*Â*Â*Â* |Â*Â*Â*Â*Â*Â*Â* | Â*Â* GND --------+------------------+Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* +--------+ So now we notice there's an item in the circuit, which doesn't follow Ohms law. And at close to 14 amps, it's a *major* part of the circuit in this case. The Ohms law part of the circuit, is well less than 14 amps. That makes sense. I was unaware there was the need for a 'constant power' supply (or even that there was such a thing) to the CPU. And I was this close to pushing the button on the other two versions of this post, and falling into the same trap I was going to warn you about. Again, good work :-) The above isn't a complete workup of the circuit. It's intended to illustrate the principle of "traps" in engineering. I've seen a couple of people nearly ruined by stuff like this. One guy, filled a lab with smoke one day and forced an evaluation... because he was so sure he was right... And that's the only time ever, that anyone did something stupid enough to cause an evacuation. If you have a device in hand, it's much better to just *measure* it, than dreamily attempt to analyze it with a half dozen table napkins. I agree and would much rather measure something, but I didn't have a clue how to go about it in this case. I 'have' lowered my Vcore voltage in the past and that resulted in a lower CPU temperature. In my mind I equated the lower temperature to lower power consumed. Â*Â* Paul (dammit!) Thank you for your detailed explanation and sorry for wasting table napkins. :-) Charlie |
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