Hello, Just built my son a new itx pc for his room, I used an old corsair psu I had as it's only seen about 5 hours use in the years I've had it. As the computer was a haswell build, I checked to see if the psu is haswell compatible and it said it was. Built the computer and started getting bsod and a automatic restart as soon as it happened. Tried another psu and that worked fine. Plugged the corsair psu back in and the only way to get it to start was by disabling Intel C State and now it runs perfectly. Just confused as corsair says it should work fully. The specs Phanteks evolv itx case Msi B85i gaming mono Intel pentium G3258 (temporary) i7 eventually 4gb crucial ddr3 Corsair Tx750 psu 500gb hard drive 120gb ssd Kingston Corsair h75 cpu cooler Any ideas at all. Don't think it makes a difference but rather have it runs and works like it should. Sent from my D6503 using Tapatalk
That is odd. Intel C State allows the system to independently adjust core speeds to save power consumption and lower heat generation. Those dynamic changes would affect the loads seen by the PSU but I don't see why or how that would affect a PSU, unless the PSU was faulty.
The CPU goes into such a low power state that the PSU goes into UCP (Under Current Protection) and it shuts off due to being unable to deliver stable low voltages/currents to the components. I've never seen it happen, and it was largely a load of marketing spiel, but I guess it does happen. Unlucky chap. Actually, here's an article from B-T themselves. http://www.bit-tech.net/news/hardware/2013/05/01/haswell-psu/1
That's a lousy excuse and I've never seen it either (I think) but makes total sense. I note that TX750 is only a basic 80-PLUS certified PSU and I don't see here where it says it is Haswell compatible. Where did you see that? I wonder if this UCP issue was a driving force for the 80 PLUS certification committee to add 10% load requirements to Titanium? I said "I think" because I have seen PSUs not work with PSU testers (which supply only a 10 ohm load) yet fire up when attached to a motherboard. And to that, it seems a motherboard, drives, RAM and fans should be enough load to keep running.
It's not a lousy excuse, it's fact. The fact that it happens in extremely rare cases, doesn't mean it doesn't exist. The 80 PLUS is something entirely different, that's efficiency from AC to DC conversions. The PSU designers need to work on the internal workings of the PSU to get allow it to produce such low currents and voltages at a stable rate. That's the main issue, producing such a low voltage and keeping it stable is extremely difficult, especially when there's barely any current too.
A lousy excuse can still be factual! I agree on both accounts. I am just saying considering there is much more to the load factor on a PSU than the CPU, the PSU shutting down because the CPU goes, in effect, idle, makes it a lousy excuse. And yeah, I know 80 PLUS by itself is not a factor here. But one of, if not the primary principle with 80 PLUS certification is that the PSU have a relatively flat (in addition to high) efficiency response across a full range of "expected" loads. And while "zero" load is not expected, that would never happen. You still the motherboard itself and many devices (integrated and attached) drawing power - even if the CPU is sitting there doing next to nothing.
