psu ok?

[Vishal]

i upgraded by old 300watt psu a month and a half ago to a thermaltake butterfly psu 480 watt for new gpu. the values in mbm5 are as follows:


line current low high average
+3.3 3.4 3.4 3.4 3.4
+5 4.97 4.97 5.00 4.97
+12 12.59 12.52 12.65 12.59
-12 -12.89 -13.59 -10.99 -12.22
-5 -3.61 -4.79 -0.0 -4.16

why are the -12 and -5v rails so variable?

 

[Ice Czar]

because there is nothing drawing on them
they are unused and can be safely ignored

your software monitors are really only good for comparitive values
not definitive values till you calibrate them with a multimeter

+3.3V......+3.135V to +3.465V
+5V.........+4.75 to +5.25
+12V........+11.4 to +12.6

What is the correct way to test a power supply?

its likely the baseline for your +12V rail is high, and that its actually in spec

 

[Vishal]

one more question, i let mbm5 run on all day today and on the +12v line it dropped 0.36 volt at one stage? if this was the case wouldn't the pc lock up?

 

[Ice Czar]

MBM pulls its data off the SMBus (System Management Bus) and sometimes it "misses" or the Bus misses

Ive got a box right now that 3 times out of 5 will give me 2 temperature alarms saying my system temperature (not the CPU) is at 119C
I simple ignore them and it goes away and doesnt repeat

if that where actually the case Id be sitting in an oven instead of an Air Conditioned Room

I wouldnt worry about an isolated reading, but any repeating trend you can match to an activity would be another matter
like a rail dropping below spec (undershoot) when you fire up an optical or load up the CPU\GPU or overshoots when going from full load to idle with the CPU\GPU, the HDDs are a static draw except at spinup and that can actually introduce alot of instability to the rails, but since that happens at startup before MBM is able to load the only way to observe that is with a multimeter

some variation of the rails is to be expected and as long as its within the 5% varience listed above you should be OK, with a better supply, you expect less varience, and if overclocking you actively seek extreme stability (though that power is also regulated by the mobo before being fed to the CPU\RAM|AGP)

 

[Vishal]

ok thanks, makes me feel i didn't waste my money.

 

[Ice Czar]

the difference between an average PSU and a really good PSU isnt obvious until you ask it to do something unusual, like deal with a serious shift in the internal load, at the same time its dealing with a source power (AC) surge or brownout, of course you always want to make sure whatever supply you have has adequate amps per rail for what your trying to power, but the more expensive PSU do tend to let you get away with more (greater dynamic load, dirtier power, unusual configurations, stabler overclocks)

Id advise a power connditioning scheme, either a UPS or a really high quality surge protector (though that does nothing for brownouts) there are alot of advantages to eliminating potentially dirty source power, protection mechanisms in PSUs should safely shut down the PSU and components without damage if it all too much for the unit, but how well those are implemented from PSU to PSU is also a derivative of the quality of the design, more expensive PSU again having a higher level of confidence