Hi wharf rat,
As stated in my previous post, these figures are based on those taken from
pp1266-1267 of 'Scott Mueller's Upgrading and Repairing PCs, 18th Edition'.
As for the figures themselves I have assumed 2 sticks of RAM, 6 (Six) Hard
Disks, 2 Optical Drives and 2 Cooling Fans. Obviously, there is only 1
motherboard, processor and graphics card in this equation. I have implied
this from Tyrenta's first post in this thread. Looking at your figures, you
appear to be using only 1 hard disk whereas my calculations were based on 6.
Power supplies are rated at their maximum output and they can only maintain
this rating for very short bursts. The continual rating of supplies is
considerably less, typically 65%-85% of the maximum rated output. To ensure a
reasonable margin for supply capacity, assume an efficiency of 65% and add
10% to the component power consumption figures as in my previous post. Using
this criteria, whilst you might be OK running on this supply, there is little
spare capacity available. Using your figures, I get a system total of 220.4W.
Adding 10% gives 242.44W. Using a 300W supply at 85%, ie supplying 255W,
there isn't enough capacity available for another hard drive. At 65%
efficiency, ie 195W, this supply isn't capable of sustaining this system. The
350W model is better, but not all that much. At 85%, 350W equates to 297.5W
and at 65% it equates to 227.5W which is LESS than the 300W model at 85%.
Personally, for your system using the figures you quoted, I wouldn't be happy
running it with anything less than a 400W supply.
Dwarf
"the wharf rat" wrote:
Quote:
> In article <DF44A77E-A389-4A6F-A798-D2BD970D6B20@xxxxxx>,
> Dwarf <Dwarf@xxxxxx> wrote: Quote:
> >
> >If you are using average rated components, I recommend a supply of 650W.
>
> Well, that's just silly. There must be something wrong with your
> figures because even a decent 380 watt PS is perfectly adequate for an
> ordinary desktop system.
>
> For instance, I make an 80mm case fan to be 12v x .15a = 1.8 watts.
> Are you figuring startup current as your steady state? That would only
> apply to motor driven parts like fans and drives. That's momentary and
> the other components aren't drawing anywhere near peak when it happens.
> And what x86 CPU uses 150 watts? Max current for an AMD X2 is 89. Some
> of the Intel quads get as high as 130...
> Quote:
> >Motherboard 50W 75W 62.5W 15w
> >Processor 25W 150W 87.5W 90w
> >RAM 10W 30W 20.0W 6w
> >Graphics 25W 200W 112.5W 60w
> >Hard Disk 90W 180W 135.0W 14w
> >Optical 30W 70W 50.0W 30w
> >Cooling Fan 6W 10W 8.0W 1.8wx3=5.4w
>
> My figures are closer to 250 peak 180 steady state... So a
> 300-350w power supply should be fine for normal usage...
>
>