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Getting shut down at low temps? - Page 2

post #11 of 13
Thread Starter 
After doing some learning about power supplies I just wanted to offer my under-educated opinion on why I was getting those shut downs. On the EVGA 750B PSU I was using it has 4x 12V rails @20A. The GTX 780 Ti specs 46A from the 2x 8-pins power connectors. Looking at the configuration of the rails and connectors on the PSU I was able only to get 40A max as the PCI-E power cables (4 of them) are run on only 2 rails. Which is why I was pretty much fine when I wasn't OC'd, I may have been a few Amperes short but apparently close enough. When I overclocked, needing more Amps, it triggered the over-current protection.

Voila. That's the best explanation I could come up with, no one actually suggested but if I understand correctly (and I probably do) this is what was happening. I'm not sure what the rails are like in my 850W but they were obviously hefty enough to handle the 46A.

Somebody who knows power supplies: The HX650 (my intended replacement) has a single 12V rail @ 54A. Is this 54A going to be enough for the rest of my system? (Pump, 5 fans, 4770k)
post #12 of 13
This is the NEX 750 correct? That Psu isn't very good. However the higher wattage G2 and P2 lineup based on the super flower leadex series is very very good. They just came out with a 750&850w.i see you resolved this with a new psu.
post #13 of 13
Quote:
Originally Posted by cjt0 View Post

Somebody who knows power supplies: The HX650 (my intended replacement) has a single 12V rail @ 54A. Is this 54A going to be enough for the rest of my system? (Pump, 5 fans, 4770k)

I don't pretend to know masses about PSUs, but from that you can assume you have 8amps spare (ignoring variables which affect output such as initial loads, temperature variances etc and using wildly speculative numbers!).
8amps at 12v is 96w remaining. So assuming the pump is around 0.5a, hard disk at 0.8a,5x fans at 0.2a each, motherboard/ram at *shrugs* 1a? Cpu has a tdp of at least about 90w... thats not to say everything will want all of this at once etc, but you might be pushing your limits a little. If you assume that overcurrent protection doesn't kick in until 110% (again, guessing) then you're pretty safe tbh.

All of this assumes your psu is happy running its rated amounts though! smile.gif
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