So, I recently built a new system. I figured out what motherboard I wanted, what cpu, how much memory and disk and then I when and used a couple of the online system wattage calculators and got somewhere between 500 to 650 watts. I could not get (find) a PSU with the right connectors for the motherboard so I ended up getting Silverstone Zeus 750 watt supply (yea, overkill). I then got a UPS from a local store. They had a sale and a higher end UPS turned out to be cheaper than a 600 watt unit, so I got a APC UPS BX1500LCD (865 watt) (again, overkill but nice). What is interesting about this UPS is that it can show the current wattage used by your system on its LED (along with other stuff). Now, my strategy for constructing the new system was to pick a motherboard that was build for high-end power and then pick cool components; I am a developer, not a game player and this system will house MythTV and Asterisk someday, well as serve as a development box. So, what I ended up with was:
ASUS P5Q Deluxe Intel quad core QX9550 95 watts max for $550 (the QX9650 is 130 watts at $1000) 8GB CORSAIR (DOMINATOR) TWIN2X4096-8500C5DF Asus EN7300GT silent graphics board idle: 8.7 Watts max: 16.1 Watts 2 WD VelociRaptor Model: WD3000GLFS 300 Read/Write 6.08 Watts Idle 4.53 Watts Standby 0.42 Watts Sleep 0.42 Watts 2 WD Caviar GP Model: WD10EACS 1 TB Read/Write 7.50 Watts Idle 4.0 Watts Standby 0.97 Watts Sleep 0.97 Watts ASUS V60 cpu cooler (overkill) SAMSUNG SH-S203N DVD/CD RW Logitech SBF-90 Black 3 Buttons 1 x Wheel Logitech 967738-0403 Black 104 Normal Keys SST-ST75ZF Zeus power supply (overkill) APC UPS BX1500LCD (overkill, but very nice) Lian Li PC-A71 Black (overkill, but very, very nice) BIOS 0803 Fedora 9 64
Now, with no applications running, idle, according to the UPS the system uses 70 watts. The highest wattage I can get it to use running bunches of parallel compiles is about 125 watts.
My question is: whats with the online wattage estimators? Are they all implemented by folks selling power supplies who want to sell users bigger ones than are needed?
In terms of power needs, I ended up way over-specing $$ the system. Basically, I ended up with a system that uses as much power as a 120 watt light bulb.
Richard
Rich Emberson wrote:
So, I recently built a new system. I figured out what motherboard I wanted, what cpu, how much memory and disk and then I when and used a couple of the online system wattage calculators and got somewhere between 500 to 650 watts. I could not get (find) a PSU with the right connectors for the motherboard so I ended up getting Silverstone Zeus 750 watt supply (yea, overkill). I then got a UPS from a local store. They had a sale and a higher end UPS turned out to be cheaper than a 600 watt unit, so I got a APC UPS BX1500LCD (865 watt) (again, overkill but nice). What is interesting about this UPS is that it can show the current wattage used by your system on its LED (along with other stuff). Now, my strategy for constructing the new system was to pick a motherboard that was build for high-end power and then pick cool components; I am a developer, not a game player and this system will house MythTV and Asterisk someday, well as serve as a development box. So, what I ended up with was:
ASUS P5Q Deluxe Intel quad core QX9550 95 watts max for $550 (the QX9650 is 130 watts at $1000) 8GB CORSAIR (DOMINATOR) TWIN2X4096-8500C5DF Asus EN7300GT silent graphics board idle: 8.7 Watts max: 16.1 Watts 2 WD VelociRaptor Model: WD3000GLFS 300 Read/Write 6.08 Watts Idle 4.53 Watts Standby 0.42 Watts Sleep 0.42 Watts 2 WD Caviar GP Model: WD10EACS 1 TB Read/Write 7.50 Watts Idle 4.0 Watts Standby 0.97 Watts Sleep 0.97 Watts ASUS V60 cpu cooler (overkill) SAMSUNG SH-S203N DVD/CD RW Logitech SBF-90 Black 3 Buttons 1 x Wheel Logitech 967738-0403 Black 104 Normal Keys SST-ST75ZF Zeus power supply (overkill) APC UPS BX1500LCD (overkill, but very nice) Lian Li PC-A71 Black (overkill, but very, very nice) BIOS 0803 Fedora 9 64
Now, with no applications running, idle, according to the UPS the system uses 70 watts. The highest wattage I can get it to use running bunches of parallel compiles is about 125 watts.
My question is: whats with the online wattage estimators? Are they all implemented by folks selling power supplies who want to sell users bigger ones than are needed?
In terms of power needs, I ended up way over-specing $$ the system. Basically, I ended up with a system that uses as much power as a 120 watt light bulb.
Richard
Watts are simple, you just add them up. When I add up yours, I get 114.5 max load for the items you listed. I would guess then that the 125 watts you are seeing is probably pretty close. The power supply you bought is probably bigger than you need but the UPS, if you want to run on the battery more than a couple of minutes, is probably undersized.
If I were going to build a computer, I would probably size my power supply for twice the expected load plus a little to account for things I don't think of. Now it is possible to put a lot of load on USB ports with external drives or other equipment so you would want to allow some more for that.
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Rich Emberson wrote: <snip>
APC UPS BX1500LCD (865 watt) (again, overkill but nice).
not over kill, but extra run time.
http://www.apcc.com/products/runtime_for_extendedruntime.cfm
your ups should be in neighborhood of a back-ups rs [shown as br1500];
load time watts mins. 865 3 400 15 300 23 200 40 100 60
load wattage is design of system and can not be increased.
run time is determined by battery amp/hour. most apc ups have 2 12 v gell cell batteries in series. if you want to increase your run time, you can use more cells external of case. just use 2 'y' spade connectors, run wires [12 awg or 10 awg] to external batteries.
my only complaint about apc is that they use mov [metal oxide varistors] for surge and spike.
one day i hope they will change and use sasd [silicon avalanche suppressor diodes] made by 'transtector', http://www.transtector.com. check their site and you will see why i have installed them on all my clients systems.
- -- tc,hago.
g .
in a free world without fences, who needs gates.
learn linux: 'Rute User's Tutorial and Exposition' http://rute.2038bug.com/index.html.gz 'The Linux Documentation Project' http://www.tldp.org/ 'HowtoForge' http://howtoforge.com/
Rich Emberson wrote:
So, I recently built a new system. I figured out what motherboard I wanted, what cpu, how much memory and disk and then I when and used a couple of the online system wattage calculators and got somewhere between 500 to 650 watts. I could not get (find) a PSU with the right connectors for the motherboard so I ended up getting Silverstone Zeus 750 watt supply (yea, overkill). I then got a UPS from a local store. They had a sale and a higher end UPS turned out to be cheaper than a 600 watt unit, so I got a APC UPS BX1500LCD (865 watt) (again, overkill but nice). What is interesting about this UPS is that it can show the current wattage used by your system on its LED (along with other stuff). Now, my strategy for constructing the new system was to pick a motherboard that was build for high-end power and then pick cool components; I am a developer, not a game player and this system will house MythTV and Asterisk someday, well as serve as a development box. So, what I ended up with was:
ASUS P5Q Deluxe Intel quad core QX9550 95 watts max for $550 (the QX9650 is 130 watts at $1000) 8GB CORSAIR (DOMINATOR) TWIN2X4096-8500C5DF Asus EN7300GT silent graphics board idle: 8.7 Watts max: 16.1 Watts 2 WD VelociRaptor Model: WD3000GLFS 300 Read/Write 6.08 Watts Idle 4.53 Watts Standby 0.42 Watts Sleep 0.42 Watts 2 WD Caviar GP Model: WD10EACS 1 TB Read/Write 7.50 Watts Idle 4.0 Watts Standby 0.97 Watts Sleep 0.97 Watts ASUS V60 cpu cooler (overkill) SAMSUNG SH-S203N DVD/CD RW Logitech SBF-90 Black 3 Buttons 1 x Wheel Logitech 967738-0403 Black 104 Normal Keys SST-ST75ZF Zeus power supply (overkill) APC UPS BX1500LCD (overkill, but very nice) Lian Li PC-A71 Black (overkill, but very, very nice) BIOS 0803 Fedora 9 64
Now, with no applications running, idle, according to the UPS the system uses 70 watts. The highest wattage I can get it to use running bunches of parallel compiles is about 125 watts.
My question is: whats with the online wattage estimators? Are they all implemented by folks selling power supplies who want to sell users bigger ones than are needed?
In terms of power needs, I ended up way over-specing $$ the system. Basically, I ended up with a system that uses as much power as a 120 watt light bulb.
Richard
You only need massive power supplies in a desktop if you're running high-end video cards or something else that needs separate power inputs. Enjoy your very long UPS runtime.
-- Chris
On Fri, Aug 22, 2008 at 1:40 PM, Christopher Snook csnook@redhat.com wrote:
You only need massive power supplies in a desktop if you're running high-end video cards or something else that needs separate power inputs. Enjoy your very long UPS runtime.
In my experience, peak power usage can be much higher than the average power usage.
e.g., at boot time the system uses lots of power to spin up the drives and fans. Once their rotational velocity is established, power usage can drop to 50% of peak and stay down.
The other line of reasoning I've heard for buying an over-sized power supply is because running the power supply closer to capacity will shorten its life. Also, power supplies may be more efficient running at a fraction of their maximum rated capacity. i.e., a 200 watt power supply delivering 150 watts of power is less efficient than a 450 watt power supply delivering 150 watts of power. Maybe someone who really knows can respond to this point.
Mike
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Michael Semcheski wrote:
The other line of reasoning I've heard for buying an over-sized power
you are correct.
if you log apc site, then go to 'learning', they may still have 'white papers' that will give you guide lines on selecting ups.
heading into development as you stated, it would be very good for you to check what all apc has in 'learning' page.
- -- tc,hago.
g .
in a free world without fences, who needs gates.
learn linux: 'Rute User's Tutorial and Exposition' http://rute.2038bug.com/index.html.gz 'The Linux Documentation Project' http://www.tldp.org/ 'HowtoForge' http://howtoforge.com/
"Rich Emberson" emberson.rich@gmail.com writes:
My question is: whats with the online wattage estimators? Are they all implemented by folks selling power supplies who want to sell users bigger ones than are needed?
The estimate you found for 650-750 watts for your 70-140 watt system does seem a bit much, no matter how you slice it. Maybe they thought you were using an overclocked system that could double as a room heater in the winter???
As for the UPS, I have no problem overrating the UPS. UPS's often beat up the batteries quite a bit more than I'd like to see. If you see the run-time gets much more than 2x longer when you reduce the load by 2x you can tell that the batteries were asked to put out more current than they wanted to. For the way APC rates their stuff, running at 25%-50% of rated load doesn't sound that extravagant. (I've got the Back-UPS RS 1500 and am running at 29% with the monitor on and 20% with it off. That feels about right.)
-wolfgang
Michael Semcheski wrote:
On Fri, Aug 22, 2008 at 1:40 PM, Christopher Snook csnook@redhat.com wrote:
You only need massive power supplies in a desktop if you're running high-end video cards or something else that needs separate power inputs. Enjoy your very long UPS runtime.
In my experience, peak power usage can be much higher than the average power usage.
e.g., at boot time the system uses lots of power to spin up the drives and fans. Once their rotational velocity is established, power usage can drop to 50% of peak and stay down.
Yes. This is why I have a 350W power supply on my desktop that peaks at 117W under sustained load. 750W is pushing it. A lot of that power is going to be reserved for PCIe rails, which you're not using unless you have high-end video cards, and it's no help during spin-up. You'll bleed a few watts on those rails just keeping them hot, since the power supply has no way of knowing whether the lead is dangling in the air or hooked up to a device that happens to not be drawing power at the moment.
The other line of reasoning I've heard for buying an over-sized power supply is because running the power supply closer to capacity will shorten its life. Also, power supplies may be more efficient running at a fraction of their maximum rated capacity. i.e., a 200 watt power supply delivering 150 watts of power is less efficient than a 450 watt power supply delivering 150 watts of power. Maybe someone who really knows can respond to this point.
You're very right about the lifespan when the power source is unclean. If you have a good UPS, this is much less of an issue.
As for efficiency, the peak is usually somewhere in the middle. 80+ certification tests at 20%, 50%, and 100%, and the enhanced certifications have stricter requirements at 50% than at the extremes.[1] I'm sure there's more variability among low-end supplies, but if you've got a 350W and a 750W power supply of equal quality, and both are drawing 120W from the wall, the 350W supply running at 34% load is probably generating a lot less heat than the 750W power supply at 16% load.
-- Chris
[1] http://www.80plus.org/manu/psu/psu_join.aspx (Mouse-over for testing requirements.)
Michael Semcheski wrote:
On Fri, Aug 22, 2008 at 1:40 PM, Christopher Snook csnook@redhat.com wrote:
You only need massive power supplies in a desktop if you're running high-end video cards or something else that needs separate power inputs. Enjoy your very long UPS runtime.
In my experience, peak power usage can be much higher than the average power usage.
e.g., at boot time the system uses lots of power to spin up the drives and fans. Once their rotational velocity is established, power usage can drop to 50% of peak and stay down.
This is correct.
The other line of reasoning I've heard for buying an over-sized power supply is because running the power supply closer to capacity will
This may or may not be correct. What kills most components like that is heat. If you conduct the heat away, the PS will last a long time. Running at reduced power helps by not generating as much heat. Sort of.
shorten its life. Also, power supplies may be more efficient running at a fraction of their maximum rated capacity. i.e., a 200 watt power
"May" is definitely the watchword here. SMPSs like a minimum load. Below that, they lose regulation, and some will explode. So, many PSs include a minimum load inside them. This minimum load is absolute waste of energy. Running an SMPS at very light load results in low efficiency. I'm not an expert with UPSs, but I'm sure they use some sort of SMPS to generate a sort of "stepped sine wave", and suffer from some of the same issues. Anyway, using an ordinary PC power supply which is way overrated can result in low efficiency.
supply delivering 150 watts of power is less efficient than a 450 watt power supply delivering 150 watts of power. Maybe someone who really knows can respond to this point.
Mike