[mythtv-users] *Solution* Capture Card Power Requirements

Michael T. Dean mtdean at thirdcontact.com
Mon Aug 24 18:44:42 UTC 2009


On 08/24/2009 02:22 PM, James Crow wrote:
> After several helpful replies I found two problems with my setup.
>
> 1) The Antec PSU (vintage 2004 I think) had at least two bad caps. I 
> have no idea if it caused any other problems. It has since been 
> replaced by an OCZ 600W 80 Plus unit. I am now drawing 118 watt at 
> idle vice ~145 watt with the Antec. Probably will save me $2/month in 
> power.

80 PLUS ftw!  I saw similar savings (though my before/after were a bit 
lower): http://www.gossamer-threads.com/lists/mythtv/users/371460#371460

Note, also, that 80 PLUS only guarantees 80% + efficiency from 20% to 
100% load, so if you're only drawing 118W, you're just under the 20% 
marker.  I recommend getting the 80 PLUS lab tests for the specific PSU 
you're using to see if that's A Bad Thing.  Although they don't test at 
below 20%, you can usually extrapolate for a "small" interval beyond the 
20% load line:

http://www.80plus.org/manu/psu/psu_join.aspx

I'm guessing: 
http://www.80plus.org/manu/psu/psu_reports/SP169.1_OCZ_OCZ600MXSP_600W_Report.pdf
which wouldn't be too bad to use with your current draw, though a 
lower-power PSU might actually increase efficiency by a percent or 2.  
And, if you do decrease the number of HDD's (or otherwise reduce power 
requirements), you may actually use more total power due to efficiency 
losses (as many PSUs--even the 80 PLUS units--tend to lose efficiency 
quickly when "out of range")...

> Not enough to pay for the supply, but at least I have stable power now.

Not in the short term, but...  ;)  Note, also, that it's not difficult 
to find 80 PLUS PSU's in the $40 and lower range if you buy when they're 
on sale.  I've bought all 7 of mine for $29.99 or $39.99 with free S&H.  
Mine are also all 400W-430W PSU's.  At that rate, saving a couple 
dollars per month can recoup cost before too long.

I'm not saying it's worth replacing your brand new PSU at your own 
expense for the efficiency savings (even for those who are using 
non-80-PLUS-PSUs).  However, if you need to replace a PSU for another 
system that uses more power, you might want to buy a smaller PSU and use 
it for this system, then put the OCZ 600W in the other system.

Mike



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