Quote:
Originally Posted by metaschima
Try using the calculator at the link that I posted. With the 30% capacitor aging it recommend 253 W.
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i7-3770, 90% TDP, 1 Green SATA, 90% system load, 100% CPU load, 30% cap aging, and everything else at defualts I get 154 watts minimum, 204 watts recommended.
Code:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket LGA 1155
CPU: Intel Core i7-3770 3400 MHz Ivy Bridge
CPU Utilization (TDP): 90% TDP
ATTENTION: FOR PERSONAL, NON-COMMERCIAL USE ONLY
Green SATA: 1 HDD
Keyboard and mouse: Yes
System Load: 100 %
Capacitor Aging (+ W %): 30 %
Minimum PSU Wattage: 154 Watts
Recommended Wattage: 204 Watts
I spose you included a DVD drive as well but even then I get only 192/242-
Code:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket LGA 1155
CPU: Intel Core i7-3770 3400 MHz Ivy Bridge
CPU Utilization (TDP): 90% TDP
ATTENTION: FOR PERSONAL, NON-COMMERCIAL USE ONLY
Green SATA: 1 HDD
DVD-RW/DVD+RW Drive: 1 Drive
Keyboard and mouse: Yes
System Load: 100 %
Capacitor Aging (+ W %): 30 %
Minimum PSU Wattage: 192 Watts
Recommended Wattage: 242 Watts
But that is the wrong CPU, and including a DVD is bit off. Maybe the system does have a DVD drive, but I wouldnt assume that. Assuming that and using the numbers generated to show what you think the system needs is skewing things more.
Using no DVD and the correct CPU it drops to 116/166-
Quote:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket LGA 1155
CPU: Intel Core i7-3770T 2500 MHz Ivy Bridge
CPU Utilization (TDP): 90% TDP
ATTENTION: FOR PERSONAL, NON-COMMERCIAL USE ONLY
Green SATA: 1 HDD
Keyboard and mouse: Yes
System Load: 100 %
Capacitor Aging (+ W %): 30 %
Minimum PSU Wattage: 116 Watts
Recommended Wattage: 166 Watts
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Even at 0% added for capicitor aging its still 90/140-
Code:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket LGA 1155
CPU: Intel Core i7-3770T 2500 MHz Ivy Bridge
CPU Utilization (TDP): 90% TDP
ATTENTION: FOR PERSONAL, NON-COMMERCIAL USE ONLY
Green SATA: 1 HDD
Keyboard and mouse: Yes
System Load: 100 %
Minimum PSU Wattage: 90 Watts
Recommended Wattage: 140 Watts
Compare that to what is measured by Ulysses_
Quote:
Originally Posted by Ulysses_
Confirmed. It actually pulls 88 W from the electricity mains (as measured by looking at the house meter). This is with your recommended Corsair PSU, the CPU at 100%, GPU at 95%, and a disk benchmark test running.
With the old DC-to-DC PSU under the same load the system pulls 78 W (as measured with a DC amp meter and a DC voltmeter).
So connecting directly to the batteries only increases run-time by 88/78/0.94-1 = 20%. Not worth the risk.
(The 0.94 figure is the efficiency of the inverter as given in its spec).
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BTW the actual power consumption of the computer is going to be less than 88 watts, or even 78 watts. Assuming that the PicoPSU was 95% efficient thats 73 watts real draw 'at the motherboard'.
Those are draw figures, and even with high efficiency PSUs there will be some loss.
Also, its worth remembering that while things have gotten better, most PSUs deliever lower efficiency at very low loads. In general they are most efficient at 40-60% of labeled load, which is another reason why people suggest massive PSUs...you dont need many overclockers at the bleeding edge of stability to figure out that a huge PSU, much larger than needed, can provide that tiny bit more staiblity that turns the system from 10 BSODs a gaming session to just 1 or 2.....
But that really doesnt matter to general users, and any advantanges provided by massively oversized PSUs is outwieghed by other factors IMO.
Quote:
Originally Posted by metaschima
However, I recommend adding 50 - 100 W to this value, this is to account for possible poor labeling and manufacturing quality, and for future expansions and to keep the PSU running cooler. With a graphics card, you should add another 50 - 100 depending on the card.
EDIT: You may say that the + 50-100 W is a fudge factor, and you may be right.
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There is a reason why it has 'Minimum PSU Wattage' and 'Recommended Wattage'.
The minimum is what it thinks a 'safe' minimum is...its already allowing for 'bad' manufacturing, and differing power draws from parts you'd think should use the same power.
As we can see from Ulysses_ data, its increased by quite a large factor (73 watts real vs 90 watts bare minimum).
The recommended wattage is has already allowed for not only dodgy/higher than expected power draw parts, but has now included 50 watts for future expansion.
What you are doing is 2nd guessing a number thats a 'safe' number with a 2nd guess already included.
That is taking something thats already fudged (the original 'minimum' power draw), then had some arbitary 50 watts added to it, then said you need to add more again for exactly the reasons why the original is fudged (differing power draws, differening manufacturing quality, etc.) and to double up on the 'for future expansion'. Then added more again in case someone might want a video card.
I'd assume that anyone happy with the intel HD video isnt going to ever bother adding a video card, and if they did its not going to be some gamers monster.
There is a big difference between a 'general' system, and a system built for low power draw. Would you suggest a V8 for a mini 'just in case you ever want to tow a caravan'?
Quote:
Originally Posted by metaschima
EDIT: You may say that the + 50-100 W is a fudge factor, and you may be right. From experience, however, I always add this because I've been burned in the past for buying PSUs on a budget. The PSU can damage other components too when it fails, don't cheap out on it or you'll pay more in the end.
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Which is exactly why I was saying that overstating PSU requirements is a bad idea. It doesnt matter so much at the lower and/or smarter end, if you tell people who are buying 'general' systems with midrange video cards they need at least 650 watts but 750 watts is better, they are more likely to buy some dodgy yum cha PSU thats cheap but _says_ its 850 watts.....