Discussion Forums > Technology
Help me diagnose this shit
kitamesume:
--- Quote from: Ivon on December 14, 2012, 07:19:31 PM ---
--- Quote from: kitamesume on December 14, 2012, 05:04:01 AM ---^no because most, if not all, of the PSU has a peak non-continuous rating of 1.5-2.0 times their continuous capacity, thats how the generic PSU gets their 500watts max rating.
--- End quote ---
So you're saying you shouldn't have a buffer above what is recommended by the video card?
-Do believe that recommendation factors in a 'typical system' (CPU, RAM, HDD, etc) in addition to what the card will need.
Probably not understanding what you mean. For some reason when I red "how the generic PSU gets their 500watts max rating" I think of the Wattage listed on the side in large print....which would mean the continuous rating is something like 250watts.
--- End quote ---
did i ever say that you shouldn't add a buffer? where did i say it?
now a day's PSU are true rated at it's continuous output, GPU manufacturer's suggested PSU capacity factors in generic PSU's retarded labeling, if you've noticed why they even recommend you to use a 400watt PSU on a HD7750 that doesnt even use more than 60watts then continue reading below.
if you think the recommended PSU capacity is just about right, think again.
(click to show/hide)notes: power consumptions idle avg max
i5-3570K (stock settings) 55 82 109 watts (interpolated - http://www.xbitlabs.com/articles/cpu/display/core-i7-3770k-i5-3570k_8.html )
i3-2100 41 60 80 watts (interpolated - http://www.xbitlabs.com/articles/cpu/display/celeron-g540-g440_7.html )
G540 39 55 74 watts (interpolated - http://www.xbitlabs.com/articles/cpu/display/celeron-g540-g440_7.html )
motherboard + ram power consumptions 25 50 50 watts (approximations)
HD7850 power consumptions 10 87 101 watts (http://www.techpowerup.com/reviews/AMD/HD_7850_HD_7870/24.html )
HD7770 power consumptions 7 66 83 watts (http://www.techpowerup.com/reviews/Sapphire/HD_7770_Vapor-X/26.html )
HD7750 power consumptions 5 41 43 watts (http://www.techpowerup.com/reviews/ASUS/HD_7750/24.html )
HardDrive 7200rpm avg power consumptions ?? 8 30 watts (approximations)
Dell 18.5 inch IN1912H power consumptions 2 18 23 watts (manufacturer)
-------------------------------------------------------------------------------------------
i5-3570K + MB + HD7850 + 1HDD + monitor 92 245 312 watts
i5-3570K + MB + HD7850 + 4HDD + monitor 92 269 402 watts
i3-2100 + MB + HD7770 + 1HDD + monitor 75 202 266 watts
G540 + MB + HD7750 + 1HDD + monitor 71 172 220 watts
G540 + MB + HD7750 + 4HDD + monitor 71 196 310 watts
PS: avg power consumption means they're working at their normal state, not fully loaded, not idle.
PSS: i included the monitor, which obviously shouldn't be, although its there for that "extra baggage".
now tell me, how'd a 220watt setup got a 400watt recommended (or higher) psu capacity?
like i said, most true PSUs have a non-continuous peak output of 1.5-2.0 times higher than their rated continuous output, which means a 500watt PSU can output 750-1,000watt for a few milliseconds.
spike surges from cold boot doesn't last more than a hundred millisecond, the spike surges aren't caused by the components of a computer but by the inductors when they charge up, kill-a-watt just has a slow poll-rate to even mark how long the spike lasted, you'll need an oscilloscope to do that.
this would mean the PSU can handle the aggressive spike without tripping the OCP, although tight OCP settings could interpret that surge as a short circuit.
you can run a generic PSU at it's rated wattage for not much more than a second or two, after that it fries.
Pentium100:
--- Quote from: kitamesume on December 15, 2012, 04:54:45 AM --- spike surges from cold boot doesn't last more than a hundred millisecond, the spike surges aren't caused by the components of a computer but by the inductors when they charge up
--- End quote ---
Capacitors. Inductors cause voltage spikes when they are diconnected, capacitors cause current spikes when they are connected.
Also, a hard drive uses a few times more power to spin up than when it is already spinning. 10 hard drives spinning up at once can cause a significant load (this is why server hard drives can be made to delay spin up or to wait for a command to spin up - then the controller can spin them up one by one instead of all at once). This surge lasts about 10 seconds.
kitamesume:
we were talking about equivalent load resistances being too low thats causing the power consumption spikes, inductors acts as a short circuit when its not charged thats what i meant, same thing applies to capacitors.
how old of a harddrive are we talking about o.o, modern harddisk spin-up current draw rarely pushes over 2.5A, thats 30watts which isn't far off my approximations (although i guess i should drop the avg wattage of the hdd).
http://www.pcguide.com/ref/hdd/op/spinPower-c.html
PS: i've done this since quite a long time ago, i built that table so i can easily calculate wattage figures easily, imho since theres a table i could just fill in the blanks and do some simple math.
Pentium100:
--- Quote from: kitamesume on December 15, 2012, 06:28:00 PM ---we were talking about equivalent load resistances being too low thats causing the power consumption spikes, inductors acts as a short circuit when its not charged thats what i meant, same thing applies to capacitors.
--- End quote ---
Inductor acts like an open circuit when it is not "charged". If you connect an inductor to a voltage source, initially there will be no current and the current will slowly increase until it reaches some steady state. Inductor resists the change in current, so when you plug it in it resists the change from 0A to whatever.
--- Quote ---how old of a harddrive are we talking about o.o, modern harddisk spin-up current draw rarely pushes over 2.5A, thats 30watts which isn't far off my approximations (although i guess i should drop the avg wattage of the hdd).
--- End quote ---
0.5A normal, 2.5A on spin up - so that's 5 times more. If you have 10 hard drives, the normal power consumption will be ~60W, but when they all are spinning up at once it would be 300W...
kitamesume:
ah right yes, i might've remembered it in the wrong way, since an inductor acts as a high resistance circuit to high frequency signals.
but i had my estimated power consumption of the harddrive at 25W means i've factored in the spin-up power consumption, and since its not exactly 2.5A my estimation of 25W isn't too far off.
can you please stop pushing the harddrives as the main cause, generally regular desktop doesn't even have more than 4harddrives in them, even if you factor in 4harddrives on my chart it still doesn't hit 400watts.
a NAS on the other hand is a fileserver.
edit: for simplicity's sake i adjusted the chart.
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