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Old 04-15-2014, 10:55 AM   #31
metaschima
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The PSU only draws as much power as is required by the system, so a larger PSU will NOT consume significantly more power than a smaller PSU. In fact a smaller PSU that is running near its limit will use more power (wasting it as heat) than a larger one further from its limit. Adding 50-100 W to the estimate is good idea IMO, unless you already factor in capacitor aging, which adds this much already.
 
Old 04-16-2014, 10:38 AM   #32
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Quote:
Originally Posted by metaschima View Post
I used:
http://www.extreme.outervision.com/p...ulatorlite.jsp
To estimate the required power. Make sure to factor in 20-30% capacitor aging. With that 250W is just barely cutting it. 350W would have been a better choice. If you ever plan on getting a decent graphics card get 450W, more for a high-end graphics card.
PSU 'calcualtors' already overestimate the required power.....and for that system, 250watts should be fine, even if you take into account aging (and since its one of the 'pcio PSUs that use a laptop sytem 110/120/230/240v->12v power brick, that is the most likely source of any PSU issues)

That system should be pulling less than 120watts @ max CPU load.

http://www.xbitlabs.com/articles/cpu...k_8.html#sect0

i7-3770, 16GB (4 x 4GB),. GTX 580 video card- 115.5 watts @ 100% CPU load.

Since Ulysses_ has a i7-3770T (45watts TDP vs 77watts TDP for the 'normal i7-3770) and isnt running a standalone video card, max power consumption should be even lower than 115 watts.

Quote:
Originally Posted by Ulysses_ View Post
Should I put a bigger psu next time despite the fact that the maximum power calculates to well below the 250 W of the dc-to-dc psu and say goodbye to efficient operation on caravan batteries?
I wouldnt. But having a spare normal wall pluged PSU yuo can use for testing might be an idea.

Quote:
Originally Posted by Emerson View Post
This is incorrect. If my box draws 10 A on 12 V rail and the PS cannot go over 8 A on 12 V then it is insufficient. This is just an example, but can easily happen with a 250 W PSU.
Quote:
Originally Posted by jlinkels View Post
I can do arithmetic. Such a current distribution is highly unlikely. Unless your computer has a built-in coffee maker running at 12VDC.
Actually, it can happen. The most common cause is using old ATX PSUs from when the 3.3v and 5v rails were used more than today.

The system I'm using right now (phenom II X2 sometimes unlocked to X4) refused to run properly with an older 430watt ATX PSU. It works perfectly with the 520watt 'modern' ATX PSU.

Quote:
Originally Posted by Ulysses_ View Post
Is this a common CPU socket? Or are CPU's too expensive to keep in a repair shop for such diagnosing?

Are motherboards a more common source of failure than CPU's?
Yes, its a common CPU socket. Yes, in my experience motherobards die far more than CPUs.

Quote:
Originally Posted by Soadyheid View Post
Oh Dear what a shame, I've just bought one because Asus had a greater number of Linux compatible Mobos than any other manufacturer.
I wouldnt worry about one persons opinion. Though I sort of lean that way as well, and I'd rather buy a different brand, I'm nowhere near as harsh as metaschima.

Asus used to sell only really nice stuff (under the asus brand anyway, they've made plenty of junk for OEMs). They really dropped in quality for a while, and IMO have never got back top the peaks they used to hit, but they still make some pretty nice boards. I'd probaly rather have an asus than many of the brands out there (e.g. asrock, biostar)
 
Old 04-16-2014, 12:28 PM   #33
Drakeo
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sure sounds like a power supply. Reason why. when it goes to draw watts it fails. if it was a cpu. This is where I would ask. i7 has on chip graphics. does your mother board use that or does it defer to on board graphics. Either way the moment the motherboard devices called for more watts durring boot up and the watts do
not come. Then you will be dead. no ram beeps etc.
of course miss matched ram will cause this also. and you may here a beep. but not always. If your going to buy a new mother board get a nice 500 watt psu for your i7
I know it is not needed for the cpu . It is a myth that a power supply that can do 500 watts cost you more if your devices only draw 250 watts.
Hard to believe 32 gigs of ram and your asking a 250 watt power supply to handle that.

I am amazed the power supply lasted that long with 32 gigs of ram.
you really need to read the ram manufacture warning on today's ram.

Last edited by Drakeo; 04-16-2014 at 12:38 PM.
 
Old 04-17-2014, 04:09 PM   #34
Ulysses_
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Getting an Antec 450 W supply then (you recommend any model?), and moving the old dc-to-dc psu towards the front of the case just in case it ever becomes important to increase efficiency when running off caravan batteries, eg in cloudy wheather.

I know it is a long shot, but if all 26 cables of both psu's are soldered in parallel, does this have any chance of working and saving me the trouble of plugging and unplugging? What would happen and why (only one psu would be powered on at a time)?

Last edited by Ulysses_; 04-17-2014 at 04:11 PM.
 
Old 04-18-2014, 04:19 PM   #35
selfprogrammed
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I have done repairs on many power supplies.
I have modified PSU cables to add another output.

PSU have a load resistor on the output which would load down the other power supply, even when off. You can only safely do that on PSU which are specifically made for dual PSU usage, where if one fails the other PSU takes over.

Connecting two power supplies like that would be asking for trouble.
You could no longer diagnose the two of them independently. If you ever suspected PSU problems again it would be very difficult.
I think you would be better off with the unplugging and plugging.

I have to disagree with the 500W recommendation.

See ATX12V Power Supply Design Guide.
There were major changes in the ATX12V PSU power distribution, and a change in the standard.
The power cable connectors to the motherboard are similar but not entirely compatible.
A PSU from the 80286 era, even if it was 500W, would not power a newer motherboard.

Significant change in the PSU connectors:
The -5V that used to go to the CPU was no longer needed (8080s needed -5, 586 does not).
Older motherboards needed massive current on the +5V for the CPU. Newer boards do not use it as they get CPU power using on board regulators that draw heavily on the +12V power instead.
 
Old 04-20-2014, 01:49 PM   #36
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If not 500 W, what is your recommendation for the hardware given in the OP plus a couple of Samsung 840 Pro SSD's?
 
Old 04-20-2014, 08:40 PM   #37
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As it happened, I recently ordered a new power supply at Amazon to revive an old Pentium P4 machine. I purchased a 480W PSU, not because I needed the 480 Watts, but because it was cheap and it was claimed as being silent.

So yesterday I unpacked it for actual installation. The 480W is labeled clearly with REAL BIIIIIG characters on all sides of the box. However, on the PSU itself it states that the rating is 480W peak and 330W continuously.

See, I am getting too old for this business. When I was at school, a Watt was a Watt. Yes, audio amplifiers were specified for RMS power (which was real) and Music power (which was twice as high, but fake). But for power supplies, rated power was rated power.

This was new for me. Buying 480 Watts, and getting 330 Watts. So what is the next step? 1200 Watts PMPO? (Peak Momentary Power Output). Just like in getto blasters? And then providing 230 Watts or so? Man, I really need new reading glasses or a training in reading 2014 fake specifications.

Now I understand why everyone needs at least a 480 Watts power supply to drive an i7 board. Stupid me! I even recommend 520 Watts. The bigger the better! Why not 600 Watts to drive an Atom board?

Oh and of course I fully trust the specs on the outside of the PSU. 3.3V @ 28A. And 3 wires of 0.5 mm2 or less between the PSU and the mainboard connector. Yeah, right.

jlinkels

Edit: In this machine both the chassis fan and the CPU fan would not start, although they were not stuck and turned freely. The CPU fan was rated 12V, 0.47A. I replaced the fan with a standard 12V 0.15A fan. Now I understand what happened. The PSU simply could not provide sufficient amps for the original fan. That was it of course. And no, the CPU stays within spec on 62C, even with this underpowered fan. But that is of course because the PSU can't deliver sufficient power to the CPU so it won't overheat anyway, right?

Last edited by jlinkels; 04-20-2014 at 08:46 PM.
 
Old 04-20-2014, 09:01 PM   #38
metaschima
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Yet another reason to overestimate. For my i5-based system the calculator says I can do with 300W, but I bought 450W. This is also in case I want to add a video card. Admittedly I wanted a 500W PSU, but they only had a significantly more expensive 550W of this model. As I do not game much anymore it should be adequate with a medium to low end graphics card.
 
Old 04-20-2014, 09:21 PM   #39
jlinkels
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Quote:
Originally Posted by metaschima View Post
Yet another reason to overestimate. For my i5-based system the calculator says I can do with 300W, but I bought 450W. This is also in case I want to add a video card. Admittedly I wanted a 500W PSU, but they only had a significantly more expensive 550W of this model. As I do not game much anymore it should be adequate with a medium to low end graphics card.
May I propose to the PSU calculator developers to display a figure for real power consumption and a figure for PSU rating to buy? So the rating to buy is (real consumption * 1.8). And I'll make sure I recommend buy rating in future answers to power supply question on this forum. Everybody happy.

jlinkels
 
Old 04-21-2014, 04:59 PM   #40
Ulysses_
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Aren't you going to recommend a buy rating for this thread?
 
Old 04-21-2014, 07:05 PM   #41
jlinkels
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Quote:
Originally Posted by Ulysses_ View Post
Aren't you going to recommend a buy rating for this thread?
I am not sure whether you are serious or not.
Anyway, I was not in my two latest posts. Since I only can do arithmetic with real Watts I can only recommend a power supply of a certain real rating. Not Peak Output or Peak Output Before Capacitor Degradation.

But if you insist on it: I estimate you need 220W real Watts. Add 30% for capacitor degradation: 290 Watts. Add the 80% peak/continuous labeling discrepancy: 520 Watts.

That is almost in line with Metashima's calculation. An i5 processor with a low to moderate graphics card.

It is all pure nonsense.

jlinkels
 
Old 04-21-2014, 09:19 PM   #42
selfprogrammed
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Original poster already figured what currents are needed for the hardware.
It it depressing to see suggestions to play the game of the fake power supply ratings.
I suggest only buying a power supply that has been reviewed and you have some knowlege of the actual performance.
I bought EnerMax after seeing reviews that showed that its actual performance was closer to the ratings than others. I have never had a power supply fail. Antec was my second choice as they were also trying to be reasonable in their ratings.
You buy El Cheapo off Amazon and get surprised by what you get.
It encourages the El Cheapo's to lie and cheat and you hurt the reputable manufacturers everytime you buy the El Cheapo crud. What I recommend is to read power supply reviews and buy quality, then you won't need 500W of fakey ratings.

Also, some of the fakey rated PSU caught fire during the tests. And they do skimp on the copper wire too. How well they maintain specs during load is also reviewed and is another reason not to buy that crud. You need to read a few reviews from reputable testers. Don't get fooled by fake reviews put out by the same places that make the El Cheapo PSU.

Last edited by selfprogrammed; 04-21-2014 at 09:31 PM.
 
Old 04-22-2014, 06:39 AM   #43
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Thanks. What was the review or comparative test that persuaded you to buy enermax?
 
Old 04-23-2014, 02:21 PM   #44
selfprogrammed
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The Features matched my needs.
The reviews confirmed that it would put out the current needed, and that the EnerMax ratings were not imaginary watts.
I was looking for efficiency and for a PSU that would be usable for a long time.
The EnerMax has a feature where the fan runs for a few minutes after the PSU is turned off.
This helps cool the hot computer parts at a time when there would be no other fans running (so they don't heat soak).

The reviews I like the most were from a German testing place. They put several PSU under load
and ran them overnight. Some smoked, and one caught fire. Many did not put out their rated watts, and many had poor regulation.

A review that just talks about how neat it looks or someone repeating the manufacturer's feature list has no value. Many of the user reviews are fakes. Need to find reviews from independent labs that test under load with test instruments attached.

Otherwise stick with PSU manufacturers that gotten good reviews on the expectation that their PSU ratings will be more honest, even if the particular PSU was not reviewed.

Last edited by selfprogrammed; 04-23-2014 at 02:35 PM.
 
Old 04-26-2014, 08:04 AM   #45
cascade9
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Quote:
Originally Posted by Ulysses_ View Post
Getting an Antec 450 W supply then (you recommend any model?)
Corsair CX430. Easy to get, cheap, and IMO better than the antec PSUs of similar/slightly high price range.

Quote:
Originally Posted by jlinkels View Post
As it happened, I recently ordered a new power supply at Amazon to revive an old Pentium P4 machine. I purchased a 480W PSU, not because I needed the 480 Watts, but because it was cheap and it was claimed as being silent.

So yesterday I unpacked it for actual installation. The 480W is labeled clearly with REAL BIIIIIG characters on all sides of the box. However, on the PSU itself it states that the rating is 480W peak and 330W continuously.

See, I am getting too old for this business. When I was at school, a Watt was a Watt. Yes, audio amplifiers were specified for RMS power (which was real) and Music power (which was twice as high, but fake). But for power supplies, rated power was rated power.

This was new for me. Buying 480 Watts, and getting 330 Watts. So what is the next step? 1200 Watts PMPO? (Peak Momentary Power Output). Just like in getto blasters? And then providing 230 Watts or so? Man, I really need new reading glasses or a training in reading 2014 fake specifications.
'Cheap'. Yes, in some ways we've gone back to the 'bad old days', just a new, shiney verson of it.

I've seen similar with amps and other music stuff. Yes, the quality stuff tended to be rated in RMS and PMPO was only for idiots who wanted to 'beat' the 120watts RMS amp dad has with the huge 2400watts PMOPO system....which was probably quieter, and almost certainly haD worse distortion and noise levels.

Quote:
Originally Posted by metaschima View Post
Yet another reason to overestimate. For my i5-based system the calculator says I can do with 300W, but I bought 450W. This is also in case I want to add a video card. Admittedly I wanted a 500W PSU, but they only had a significantly more expensive 550W of this model. As I do not game much anymore it should be adequate with a medium to low end graphics card.
Unless you wanted to add a 'gamers' card (GTS/GTX XXX) 450 watts is more than you'll need with an i5.

Overestimation can work both ways.....if someone thinks they 'need' 300watts, but have been told 'just get more, it wont hurt' they can end up with far worse parts. Example- the CX430 I mentioned above was about $50 at newegg. You can get a 'coolmax' 'rosewill' or other junk brand 600watter for about the same cOst or less.

Quote:
Originally Posted by jlinkels View Post
May I propose to the PSU calculator developers to display a figure for real power consumption and a figure for PSU rating to buy? So the rating to buy is (real consumption * 1.8). And I'll make sure I recommend buy rating in future answers to power supply question on this forum. Everybody happy.
There arent any hard figures. You can get a range of consumption figures for ever part depending on the measurement method. It should be 10% or less, but I've seen some very odd power consumption numbers over the years. You can also get some very screwy PSUs- if someone didnt read the PSU label, or did but doesnt know the different between peak and continuous, and actually needed 350watts+ continuous, the PSU that you bought could cause issues which the owner would never guess were PSU related.

Really, it doesnt matter much anymore, its getting hard to find anything less than about 450watts, and most motherobards manuals and manufactuers have a '500watts minimum PSU size' even if its really not needed. There are lower wattage PSUs around, but they tend to be either 'so cheap anyone should be wondering why' or they are quality brands, which brings back 'why would I pay $45 for a seasonic SS-300ET 300watt PSU when I can get a 600watter for about the same cost?'

Quote:
Originally Posted by jlinkels View Post
I am not sure whether you are serious or not.
Anyway, I was not in my two latest posts. Since I only can do arithmetic with real Watts I can only recommend a power supply of a certain real rating. Not Peak Output or Peak Output Before Capacitor Degradation.

But if you insist on it: I estimate you need 220W real Watts. Add 30% for capacitor degradation: 290 Watts. Add the 80% peak/continuous labeling discrepancy: 520 Watts.

That is almost in line with Metashima's calculation. An i5 processor with a low to moderate graphics card.

It is all pure nonsense.
Where did you get 220watts? As for 'peak/continuous', I've only ever seen junk PSUs use that, its an non-issue for quality PSUs.

I still think that 115watts is more than needed (see post #32 for more detail)-

http://www.xbitlabs.com/articles/cpu...k_8.html#sect0

With a closer to real world consumption figure, even with the maths you were using (which I dont really agree with) I end up with less than 300watts.

Last edited by cascade9; 04-26-2014 at 08:05 AM.
 
  


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