Meng-Chieh
Weaksauce
- Joined
- Apr 15, 2004
- Messages
- 65
Is there a site where you can specify your computer's specifications and then receive a calculated wattage?
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Wattage calculator
- Thread starter Meng-Chieh
- Start date
yep
http://www.jscustompcs.com/power_supply/
I don't know how accurate it is. According to it, my system shouldn't even run with my Antec True430.
http://www.jscustompcs.com/power_supply/
I don't know how accurate it is. According to it, my system shouldn't even run with my Antec True430.
Meng-Chieh
Weaksauce
- Joined
- Apr 15, 2004
- Messages
- 65
Already tried that site - gives a nice "estimate" but that is all it is, an estimate...what i'm looking for is a more specific number...
Holy shit that goatsex guy got taken care of pretty quickly. I click on this thread and I see it, then hit refresh a few seconds later and he's gone! Must be a genmay thing because someone did that a couple months ago.
Anyway, there is no calculator that will give you an accurate measurement of all your devices. Those power calculator sites are fucking bullshit; they give a worst case scenario which rarely happens in real life so that they can sell you a bigger power supply than you really need. You will have to look up the specifications for everything in your computer and add it up.
Anyway, there is no calculator that will give you an accurate measurement of all your devices. Those power calculator sites are fucking bullshit; they give a worst case scenario which rarely happens in real life so that they can sell you a bigger power supply than you really need. You will have to look up the specifications for everything in your computer and add it up.
I
Ice Czar
Guest
^ thats true to a certain extent, of course that is partitally offset by the exaggerations of most* PSU manufacturers
who combine rails but test them seperately, generally fudge specs and test at 25C when typical operating temperature is 40C
decreasing the specs by as much as 33%
so "good" calculators and charts are still pretty effective
besides, on occassion you will come close to full load
at which point you still want stability
the best PSU Calculator out there (and hes not selling anything)
takaman's Power Supply Calculator rev0.61x
HardCore PSU Info
Long Thread worth reading
its the rails not the watts
Choosing the right Power Supply
its best to be generously overpowered anyway, a PSU that runs at or near full load doesnt have as good a life expectancy as one running at half load, and of course expansion, we never seem to need less power
watts arent what you need to worry about
its the proper distribution of the amps to the +3.3V, +5V and +12V rails, and their stability
you should also consider these points
1. all calculators employ the maximum power consumption of a given component. And by its additive nature assumes that they will all be drawing at that maximum for the total. Something that rarely if ever happens
offset against
2. Many PSU manufacturers lie like dogs
about what their actual specs are, the "elite" dont need to lie
and go to great pains to point out the lies of others
-----------------------------------------------------------
PC Power & Cooling Example PDF
which shows the obvious difference between a quality PSU and junk
regarding the heatsinks in the PCP&P, note the chart at the bottom of the pdf
"Even though the ambient temperature in a power supply is at least 40C (104F),
most manufacturers unrealistically assume 25C (77F) in order to exaggerate their wattage claims.
Since the proper full-load rating is 15C higher,
these power supplies produce 33% less power than their advertised ratings
as shown on the derating chart."
---------------------------------------------------------------
Unethical PSU Marketing 101. excerpt from dansdata
Here's how to make overly optimistic power supply specifications. It's really simple.
First, power the thing up. You can make an ATX power supply that isn't connected to a motherboard turn on by grounding pin number 14 on the big motherboard power connector. It's easy to spot that pin, because it's the only one with a green wire going to it.
Use any handy bit of wire - like the paper clip in this picture - to connect pin 14 to any ground contact. The ground contacts are the ones with the black wires going to them. Presto, the PSU will turn on.
Now, break out your brick-sized power resistors and load the heck out of one of the output rails - the +5V rail, for instance. Measure the current as you increase the load, until the voltage sags unacceptably far below the rated voltage.
How do you tell what an unacceptable voltage sag is? Well, you could choose a nice conservative small permitted sag - say, 0.1 volts - so that your results are genuinely useful to your customers. Or you could just ignore the voltage and say that when a fuse (or some other component...) blows, that must have been the limit, right there.
OK. Now you've made a big fat amperage number for the +5V rail. If you blew up the PSU in the process, get another one, and repeat the process for +12V and +3.3V, and for the low current rails as well.
On no account, though, should you test more than one rail at a time. This is the key to the whole scam.
A big beefy PSU may be able to deliver 50 amps (say) on the 5V rail when nothing else is under load, and 25 amps (say) on the 12V rail when it's similarly all alone. But the 12V and 5V rails together may only be able to deliver, say, 350 watts between them, when they're both under load. Watts equals amps times volts.
In a real PC, all of the power rails will always be under load together.
But you're not testing what the PSU can really do - you're making pretty numbers for the sales brochure!
So test all of your rails alone, get an amperage figure for all of them, multiply that figure by the voltage of the rail it came from (the nominal voltage, not whatever the voltage had sagged to as the PSU pumped electrons through the dessert spoon you'd soldered to the circuit board), then take all of the resulting wattage figures and add 'em up. That's a wrap, folks. Ship it!
http://www.dansdata.com/top420p4.htm
(worth reading the whole review, as to what is important and what isnt, if not a recommendation for those particular PSUs
those are monsters anyway)
-----------------------------------------------------------------------
PSU rerviews showing "overstated" specs
http://www6.tomshardware.com/howto/20021021/index.html
http://www.anandtech.com/showdoc.html?i=1774
http://www.anandtech.com/showdoc.html?i=1841&p=1
In the budget category I highly recommend Fortron PSUs which are often rebadged look for an FSP model designation, but still look at the amps per rail, and buy more total amps\watts than you need, by a comfortable factor
Why?
Because you never need less power it seems
and because a PSU working at half load will last longer than one working at near full load.
for all mechanical and electrical components physics apply (DUH)
specifically the Arrhenius equation
which is more a rule of thumb than anything else but boils down to this:
Each 10°C (18°F) temperature rise reduces component life by 50%*.
Conversely, each 10°C (18°F) temperature reduction increases component life by 100%
and a PSU at full load is hotter than one that is not
and if you read that long threade link you will discover that instability in the power is the leading cause of fried RAM (after installation issues with ESD)
who combine rails but test them seperately, generally fudge specs and test at 25C when typical operating temperature is 40C
decreasing the specs by as much as 33%
so "good" calculators and charts are still pretty effective
besides, on occassion you will come close to full load
at which point you still want stability
the best PSU Calculator out there (and hes not selling anything)
takaman's Power Supply Calculator rev0.61x
HardCore PSU Info
Long Thread worth reading
its the rails not the watts
Choosing the right Power Supply
its best to be generously overpowered anyway, a PSU that runs at or near full load doesnt have as good a life expectancy as one running at half load, and of course expansion, we never seem to need less power
watts arent what you need to worry about
its the proper distribution of the amps to the +3.3V, +5V and +12V rails, and their stability
you should also consider these points
1. all calculators employ the maximum power consumption of a given component. And by its additive nature assumes that they will all be drawing at that maximum for the total. Something that rarely if ever happens
offset against
2. Many PSU manufacturers lie like dogs
about what their actual specs are, the "elite" dont need to lie
and go to great pains to point out the lies of others
-----------------------------------------------------------
PC Power & Cooling Example PDF
which shows the obvious difference between a quality PSU and junk
regarding the heatsinks in the PCP&P, note the chart at the bottom of the pdf
"Even though the ambient temperature in a power supply is at least 40C (104F),
most manufacturers unrealistically assume 25C (77F) in order to exaggerate their wattage claims.
Since the proper full-load rating is 15C higher,
these power supplies produce 33% less power than their advertised ratings
as shown on the derating chart."
---------------------------------------------------------------
Unethical PSU Marketing 101. excerpt from dansdata
Here's how to make overly optimistic power supply specifications. It's really simple.
First, power the thing up. You can make an ATX power supply that isn't connected to a motherboard turn on by grounding pin number 14 on the big motherboard power connector. It's easy to spot that pin, because it's the only one with a green wire going to it.
Use any handy bit of wire - like the paper clip in this picture - to connect pin 14 to any ground contact. The ground contacts are the ones with the black wires going to them. Presto, the PSU will turn on.
Now, break out your brick-sized power resistors and load the heck out of one of the output rails - the +5V rail, for instance. Measure the current as you increase the load, until the voltage sags unacceptably far below the rated voltage.
How do you tell what an unacceptable voltage sag is? Well, you could choose a nice conservative small permitted sag - say, 0.1 volts - so that your results are genuinely useful to your customers. Or you could just ignore the voltage and say that when a fuse (or some other component...) blows, that must have been the limit, right there.
OK. Now you've made a big fat amperage number for the +5V rail. If you blew up the PSU in the process, get another one, and repeat the process for +12V and +3.3V, and for the low current rails as well.
On no account, though, should you test more than one rail at a time. This is the key to the whole scam.
A big beefy PSU may be able to deliver 50 amps (say) on the 5V rail when nothing else is under load, and 25 amps (say) on the 12V rail when it's similarly all alone. But the 12V and 5V rails together may only be able to deliver, say, 350 watts between them, when they're both under load. Watts equals amps times volts.
In a real PC, all of the power rails will always be under load together.
But you're not testing what the PSU can really do - you're making pretty numbers for the sales brochure!
So test all of your rails alone, get an amperage figure for all of them, multiply that figure by the voltage of the rail it came from (the nominal voltage, not whatever the voltage had sagged to as the PSU pumped electrons through the dessert spoon you'd soldered to the circuit board), then take all of the resulting wattage figures and add 'em up. That's a wrap, folks. Ship it!
http://www.dansdata.com/top420p4.htm
(worth reading the whole review, as to what is important and what isnt, if not a recommendation for those particular PSUs
those are monsters anyway)
-----------------------------------------------------------------------
PSU rerviews showing "overstated" specs
http://www6.tomshardware.com/howto/20021021/index.html
http://www.anandtech.com/showdoc.html?i=1774
http://www.anandtech.com/showdoc.html?i=1841&p=1
In the budget category I highly recommend Fortron PSUs which are often rebadged look for an FSP model designation, but still look at the amps per rail, and buy more total amps\watts than you need, by a comfortable factor
Why?
Because you never need less power it seems
and because a PSU working at half load will last longer than one working at near full load.
for all mechanical and electrical components physics apply (DUH)
specifically the Arrhenius equation
which is more a rule of thumb than anything else but boils down to this:
Each 10°C (18°F) temperature rise reduces component life by 50%*.
Conversely, each 10°C (18°F) temperature reduction increases component life by 100%
and a PSU at full load is hotter than one that is not
and if you read that long threade link you will discover that instability in the power is the leading cause of fried RAM (after installation issues with ESD)
RancidWAnnaRIot
EspantaPajaros
- Joined
- Feb 19, 2004
- Messages
- 11,033
Can you really measure you're power through that? I mean how the hell can you measure you're devices equivalent resistance? Last time i checked manufactures don't supply that much information.
burningrave101
[H]F Junkie
- Joined
- Sep 9, 2003
- Messages
- 11,825
Those ARE more specific numbers. If you read at the very top of the page it says:
"Please Note: The Wattages listed below are maximum potential wattages for each item. The total amount this calculator figures is for all devices running at peak utilization. It is important to bear in mind that this amount will never be reached under typical operation. However we feel that this tool will give you a better idea of how much power your system will need. After all when it comes to power, it is better to be safe than sorry."
They are showing you the maximum draw for those devices. Maximum draw is what they could possibly ever draw but most likely never stand a chance of drawing that much.
Just try and stick with the brands and models that are recommended here on HardOCP and as far as wattage goes here is what i would suggest.
200-250w = Low-End System
300-350w = Mid-Range System
400-480w = High-End System
Antec, Enermax, Fortron, and PC Power and Cooling would be fine choices for a PSU brand. Antec is the one i would go with personally.
He did it in this thread a few hours ago. You can see my response at the end lol.
http://www.hardforum.com/showthread.php?s=&threadid=755823
You can imagine the shock when i was sitting here typing out my response in that thread and clicked submit and then saw that.
Damn, I missed the goat sex?
poop
Those wattage calculator sites are pretty much glorified bullshit with chrome wings.
Burningrave's advice for what power supplys to get is pretty good. A little overhead on a power supply never hurt anyone, and under extreme random load you don't want to be caught with your pants down. (heh heh, pants down and extreme random load in one sentence, thats just wrong)
I did some measuring on my system (the second in my sig) and under a steady load of CoD at 1600x1200 with uber eye candy on the system was never drawing even 200 watts from my power supply. I've got 430, so I'm safe during even the weirdest moments under a full moon.
poop
Those wattage calculator sites are pretty much glorified bullshit with chrome wings.
Burningrave's advice for what power supplys to get is pretty good. A little overhead on a power supply never hurt anyone, and under extreme random load you don't want to be caught with your pants down. (heh heh, pants down and extreme random load in one sentence, thats just wrong)
I did some measuring on my system (the second in my sig) and under a steady load of CoD at 1600x1200 with uber eye candy on the system was never drawing even 200 watts from my power supply. I've got 430, so I'm safe during even the weirdest moments under a full moon.
http://www.jscustompcs.com/power_supply/
That says i need a 315 watt power supply, note, im using a 180watt right now... that thing is NOWHERE near accurate
That says i need a 315 watt power supply, note, im using a 180watt right now... that thing is NOWHERE near accurate
burningrave101
[H]F Junkie
- Joined
- Sep 9, 2003
- Messages
- 11,825
You guys aren't listening to me. IT IS ACCURATE to the sense that it is telling you how many watts you would need for each device if that device was pulling maximum peak wattage. Under normal operation it never does this and this is why you guys are able to run much smaller PSU's. This is also an overlook of peak draw for ALL brands and types for each device. Different brands and makes will draw different amounts of power. This is just a PEAK wattage overview of how much you would need IF and i do mean IF your PC was capable of maxing out each device in your system all at once.
Well even though the calculator may accurately represent a hard drive's maximum draw or a video card's maximum draw, it doesn't accurately represent what is actually in your computer. If they list a hard drive's maximum power draw at 20 watts but your hard drive's max is 15 watts then the calculator isn't accurate with respect to your system. The max of any particular device is not necessarily the max of the device in your computer.