On Thu, 02 Mar 2017 19:12:38 -0500, Bob Engelhardt
wrote:
I measured the current (inline meter) on all the MB power lines and the
hard drives power lines. As I posted, the input was from a Kill-a-watt.
One divided by the other for efficiency.
Although the PSU is using 200w, it's rated for 400w output, so my 54W is
only 13% of rated power. (The name plate input is 10A at 115v). Maybe
efficiency goes to hell for really small loads.
I didn't have time for a proper test today. I just stuffed the
kill-a-watt meter into the bench power strip and used it to power an
HP 8200 Elite SFF desktop. Something like this with an i3 CPU:
http://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c03412787
http://h20564.www2.hp.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-c02781555
I think it has power factor correction for:
320 W active PFC 87%/90%/87% efficient at 20%/50%/100% load.
The input power consumption varied from 30 watts to 70 watts depending
on what the machine was doing. Eyeball average was about 50 watts.
Playing a video burned 70 watts. The power factor varied from 0.90 to
0.96. However, I was unable to obtain VA and watt reading pairs to
determine if the PF was for real.
However, I had no way to measure the current at the motherboard and
drives. I also couldn't find my ATX dummy load. I'll throw something
together this weekend if I have time.
My intuition is that 2 75W light bulbs in a box could be cooled by a PSU
fan. Without flames.
I don't use light bulbs as loads (except for UPS testing). Mostly, I
use power resistors and head sinks. My load is intended to simulate a
game machine, which typically burns about 350 watts with a high end
video card installed. At that power level, I need either a fan or a
bucket of water to cool the heat sink.
It's kinda wonky, but not crazily so.
Well, like I suggested... something is wrong. It's unlikely that your
PS has PF correction or is highly efficient. However, it shouldn't be
as low as 13%. Something is wrong, but I can't tell where from here.
If you have the time and inclination, you might try testing a known
good ATX power supply and see if the numbers magically improve. If
the efficiency is fairly high, then the original power supply is
broken somewhere. However, if it too shows 13% efficiency, then
there's something wrong with either your instruments, or your
methodology.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558