Quote from: DeathAndTaxes on November 11, 2013, 05:36:54 AM

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Um, yep....why do you think those PSU's were shutting off? And your "spec calculation" is over simplistic, btw...just because a PSU is rated for an overall wattage doesn't mean that an individual rail is.

Simplistic or not it was accurate. Most modern PSU provide 90% to 100% on the 12VDC rail because they do conversion of all AC power to 12VDC and then power the other rails off the 12V rail.

Sorry typo ment to say at worst efficiency was ..... Still if the efficiency was WORSE than 90%, say 88% then that only reduces the relative DC load as it compares to the observed AC load. 850W/0.88 = 956W. 850W/0.85 = 1000W. You telling me people have reported >950W at the wall?
Nonsense.

So once again 850W is fine. A single person reported a single problem with a single model of a single brand of power supply and you want to say 850W is insufficient. Strange KNC entire datacenter is powered by nothing by 850W PSU. KNC still recommend 850W. Many people are using 850W PSU without issue.

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Again, according to manufacturer's specs you could expect 87.73% @115V input. So put the lower actual rated rail wattage coupled with lower real-world efficiency and guess what? You are running that thing over-spec at time of KnC initial release and that's why those things were shutting themselves off and then coming back with a bang in some cases upon recovery.

Math isn't your strong suit is it.
840W / 0.8773 = 957W. That is about 100W higher than any has reported their unit pulling.

Actually, I have a degree in Engineering and I do technology work for a living...math is very much my strong suit. I'm telling you that those PSU's (HX850) were shutting off. I just reported to you that mine ran 950W constantly (bounced between 945 and 954) as I watched it in real time. I have seen momentary spikes up to about 975W (read 972 briefly when it happened). Since my UPS only seems to report wattage in 9W increments, it very well may have been higher. I'm pretty sure I don't have a "special unit". It's obvious (to me, at least, who seems to actually understand these things) that the failure mode related to the HX850 was caused by overcurrent protection kicking in. This failure mode could have been prevented by buying a 1000W PSU, as many people did (and those who had HX1000 reported no such problems to my knowledge). Now, you can play armchair engineer all day (as you are apt to do on these threads, and often talk out of your ass though few call you on it) but that is a fact. That is something that GE themselves verified with a hands-on test.

As for "strange" blah blah blah...um, you don't happen to remember the OTHER datacenter that had numerous boards blow up because they were running HX850's? Seriously dude, did you hit your head or are you just trying to be a revisionist historian here to serve some sort of agenda? Look back at the thread...all the info is there in gory detail. The fact that 1) KnC lucked out by using Coolermaster which seemed to have a bit of headroom in the specs and more tolerant overall and 2) they quickly released firmware which dramatically reduced power requirements has been the reason(s) that they haven't had catastrophic issues.

And to specifically address the "nonsense" thing...you sure talk with a lot of authority on how these things operate for someone who doesn't even have one. But I guess it's easier to just theorize rather than deal with actual facts gained from hands-on observations, right? Wink