About this online PSU wattage calculator...

[-Slacker-]

This one:

http://www.thermaltake.outervision.com/Power

It's pretty useful and has coverage for a lot of hardware models but I'm confused about something:

Is the calculated wattage referring to how much power my machine draws from the wall or how much is fed directly to the components?

It would seem like the latter, since different PSU's have different power efficiencies, but I'm asking because after some calculations the site then goes to recommend me models that are the same wattage as calculated power consumption (eg. ~388W calculated > 400W PSU), and other tests say I need wayyy over what the results show (eg ~430W calculated > 600/650W PSUs)

edit:

It would seem like the latter, since different PSU's have different power efficiencies

...Although it could be that they're using an average power efficiency standard for thermalake PSUs only.

edit2:

What the hell! I just pushed for 15 more watts (extra HDD) on the ~400w setup and the PSU recommendation jumped back to 600 and 650w models.

I checked to see if the lower wattage recommendations weren't some sort of isolated error or something like that and when I went down a bit from ~400w the site kept showing me 400W PSUs, so it doesn't seem to be a one-time slip up.

The patterns seems to be:

for 400W power consumption and below> 400w models

for 401W power consumption and above> 600/650w

weird

 

[yh125d]

It's because PSU calcs are inaccurate and useless. Give us your parts list and we'll tell you how much you need

 

[HOOfan 1]

I am pretty sure they are just recommending a size of PSU, and not how much power your components will draw. Hopefully they are assuming that you don't want to draw more than 65%-70% of the rated output regularly....at most.

 

[-Slacker-]

It's because PSU calcs are inaccurate and useless. Give us your parts list and we'll tell you how much you need

This one:

Phenom II x4 965 overclocked at 3.8~3.9 Ghz

Ati radeon HD5870 overclocked at stock voltage

1 SATA2 HDD, although I might want experiment with a SSD in the future too

1 DVD RW

2-3 120 mm case fans

I am pretty sure they are just recommending a size of PSU, and not how much power your components will draw. Hopefully they are assuming that you don't want to draw more than 65%-70% of the rated output regularly....at most.

That would be great actually It would pretty much mean I can just stick in a good 450w PSU and be happy with it.

 

[HOOfan 1]

This one:

Phenom II x4 965 overclocked at 3.8~3.9 Ghz

Ati radeon HD5870 overclocked at stock voltage

1 SATA2 HDD, although I might want experiment with a SSD in the future too

1 DVD RW

2-3 120 mm case fans



That would be great actually It would pretty much mean I can just stick in a good 450w PSU and be happy with it.

You could...good being the opperative word. I would go 500-550W myself though, since you are overclocking

 

[yh125d]

550vx

 

[-Slacker-]

^Yup. The test I made didn't take into account that I was overclocking the GPU as well so 550 sounds reasonable.