The most accurate PCU wattage calculator?

noisekiller · Post by **noisekiller** » Wed Mar 01, 2006 1:01 am

I wonder which is the most accurate PSU wattage calculator on the web?What do you think about this one:

http://extreme.outervision.com/index.jsp

SnooP · Post by **SnooP** » Wed Mar 01, 2006 3:52 am

Very flawed. Following problems:

uses TDP values for wattages, which are often significently higher than actual for AMD, and smaller the actual for intel. Example - venice 3000+ and 3500+ have the same TDP (67w), but obviously different actual consumptions (about 40w for 3000+, 45w for 3500+.

Overclock cpu thing is rediculous - overclock an opteron 165 to say 2.7ghz and the supposed consumption is 200w - which well beyond the capabilities of air cooling for an opteron (therefore impossible since such overclocks are often achieved on stock cooling).

No calculations of 12V rail consumption - with most psu's you'll max out the 12V rail(s) before wattage unless its a latest atx2.2.

example calc:
opteron 165 @ 2.7ghz / x1900xt crossfire / a few hard drives etc.
calculater says '702w'

example 2:
SCPR measured a p4 EE 840 / 6800gt system to draw 220w peak under
load.
http://www.silentpcreview.com/article265-page4.html
extreme psu calc suggests 400w as consumption for same basic specs

frostedflakes · Post by **frostedflakes** » Wed Mar 01, 2006 10:43 am

Yeah, it's one of the better calculators out there, but still way off. Your best bet would be to use sites such as Xbit Labs who measure actual power consumption of video cards and processors as a reference. TDP is often not a reflection of real-life power consumption. Then, if neccessary, use an online wattage calculator to find out how undervolting or overclocking effects the power consumption of your processor.

Also, in SPCR's article Power Distribution within Six PCs Athlon64 systems on the average pulled about 75% of their power from +12V, whereas P4 systems pulled 80-90% from +12V. Might be useful in getting a general idea of how much power you need on +12V for an A64 or P4 system.

noisekiller · Post by **noisekiller** » Wed Mar 01, 2006 1:54 pm

I have:

Abit NV8 //ZM-NB47J/Revoltec AirGuard 50mm@5V
AMD Athlon64 Venice 3000+@2600MHz //AC Freezer64 Pro //Revoltec AirGuard 92mm@7V
2x256Mb DDR400 Princeton
Leadtek Winfast PX6600GT TDH 128Mb // Zalman VF700-AlCu/Revoltec 80mm@5V (not yet)
Creative Soundblaster Live! 24bit 7.1
Sony CRX-300E combo drive
Benq DW1640 (not yet)
WD800JB /decoupled
1x120mm Revoltec AirGuard@5V
Thermaltake Xcontroller (crap-does only 6.5V-12V,among others)
Logitech Precision 2 USB
Logitech BV-85 USB
Logitech UltraX Flat USB

There are printer and scanner to buy,both USB and most likely internal PCI Firewire card and TV/FM Tuner...

I'm planning to buy Seasonic S12-380...will that be enough...how much do you think my PC does actually spend?

Devonavar · Post by **Devonavar** » Wed Mar 01, 2006 3:14 pm

Yes, that will be enough. Your system probably won't draw more than ~100W DC.

TooNice · Post by **TooNice** » Thu Mar 02, 2006 8:12 pm

Makes me wonder though. How hard would it be for PSU manufacturer to include some type of system load monitor?

Devonavar · Post by **Devonavar** » Thu Mar 02, 2006 11:29 pm

If Coolermaster's attempt (see numerous CM reviews) are anything to judge by, pretty difficult. The margin of error in the models I've seen has been something like +/-60W.

Adding a digital monitoring circuit would be quite non-trivial, and would probably add a fair amount to the cost of the PSU.

jaganath · Post by **jaganath** » Fri Mar 03, 2006 2:03 am

TDP is often not a reflection of real-life power consumption.

Just as a side note, TDP is not meant to reflect everyday power draw. It's for mobo and heatsink manufacturers to let them know what kind of heat and electrical tolerances to design their products to, which is why it is called the Thermal Design Power.

I know you know this already FF, but just thought I should re-iterate it.