[mythtv-users] Should I Upgrade Frontend from AMD 3200+ to AMD X2 3800+ (DualCore) ?

[Krzysztof Adamski]

On Sat, 2009-02-14 at 16:56 -0700, Brian Wood wrote:
> On Saturday 14 February 2009 16:48:26 Krzysztof Adamski wrote:
> > On Sat, 2009-02-14 at 17:42 -0500, Eric Holt wrote:
> > > On Sat, Feb 14, 2009 at 5:00 PM, Brad Templeton
> > >         Though right now I am buying all core 2 duo.   Most myth
> > >         systems end
> > >         up being up 24/7.    And being up 24/7 makes every watt of
> > >         power count,
> > >         and core 2 processors are lower power than the AMDs, unless
> > >         AMD has changed
> > >         a lot recently.
> > >
> > > Intel is still mostly producing processors that use 65w.  Check
> > > NewEgg.  There are 2 processors on there that use 35w, but both of
> > > those are single-core Celeron's.  All of the 45w processors are AMD.
> > > Then Intel finally shows back up in the 65w range (as well as quite a
> > > few more AMD processors).
> > >
> > > I have the 4850e, which is dual-core at 2.5ghz -- and 45w max power
> > > usage.  AMD also now has the 5050e, which is 2.6ghz at 45w.
> > >
> > > I have a box running the 4850e, like I said, and a 80%+ efficient PSU
> > > -- with AMD's cool-n-quiet enabled... that idles around 40w, and
> > > barely hits 100w at full load.  Compared to my other box that was 65w
> > > idle / 145w loaded -- thats a good bit of power savings.
> > >
> > > heh, I love having a Kill-a-Watt. :)
> > > --Eric
> >
> > I just had a PSU die in my desktop/frontend computer. I was wondering
> > what size of a PSU I need.
> > The existing PSU is a 400 Watt Antec earthwatts using, when doing
> > nothing the Kill-a-Watt shows a usage of 155W, and at full CPU
> > utilization it would go up to 215W when transcoding something.
> >
> > So what size of PSU do I need for this computer, is there a rule of
> > thumb for translating the Kill-a-watt usage in to the size of PSU that
> > is needed?
> 
> The Kill-a-Watt tells you how much AC power you are inputting to the PSU from 
> the wall, not how much DC power the PSU is supplying to the computer. The 
> power draw of things like CPUs, HDDs etc. is specified as how much DC power 
> they draw (after the PSU) .
> 
> The difference between the two depends on the efficiency factor of the PSU 
> itself. So an HDD that says it draws 10 watts will draw perhaps 12 watts from 
> the wall outlet, again depending on the efficiency of the PSU.
> 
> Note also that the KAW can read watts or volt-amps. Thw two are the same if 
> the power factor is 1.0, and VAs will be higher than the watts if a reactive 
> load is involved. You probably want to have the unit in watt mode.
> 
> Some power supplies run pretty inefficiently at loads that are well below the 
> rated maximum, so you would probably not want a 1000 watt PSU if you are only 
> using 200 watts.
> 
> Having said all that, a 350 or 400 watt PSU should be OK for what you want. 
> Even a 500 watt unit would probably be fine.

So to put it in a simple terms :-)
If the max draw at the KAW shows is 220W and we us a 80+ PSU that has a
99% power correcting, then (220W + 10% safety) for 242W at 80%
efficiency gives us a 290W, so a 300W 80+ PSU should be more then
enough, right?

K