I discovered that setting both jumpers jpme1 and jpme2 to 2-3 disables IPMI. On my system, which has the RAID card, I had to get in with a pair of long thin needle noses to access these jumpers. VGA works, one can get into bios with the del key, and the OS boots. ipmicfg and ipmitool report nothing, and the IPMI RJ45 port cannot be connected to. BUT power consumption is unchanged, as reported by my trusty amp-clamp, which I have to believe is accurate unless somebody can convince me that a switching power supply has a power factor significantly below 1.0. See
https://www.supermicro.com/support/faqs/faq.cfm?faq=16448 although it is not clear to me what the relationship is , if any, between Intel Management Engine and BMC/IPMI.
Sure, any day of the Week
. Even though I'm not a PFC Expert, I am regularly working with Power Converters. As I always need to stress to everybody: don't believe the Marketing Hype ! An Operating Point and Performance has to be specified at a PRECISELY Defined Operating Point. MANY Parameters are involved in that. Grid Voltage. DC-Link Voltage. Switching Frequency. AC/DC Load. Auxiliary Consumption. Reactive Power (if Active Front-End on AC side). Temperature. Etc. Otherwise it's just Marketing like "up to 95%" Efficiency or "from xxxx $". And in reality at YOUR operating point you might get 3x worse Performances for 3x higher Price
.
You might want to look into LED Lightbulps for one. Let's have a talk about Power Factor there, because that's probably as bad as it gets (for the Grid or if you have any Contactor/Relay/Breaker/Fuse installed), that's a very nice Capacitive Load that can lead to Contactors Welding or Breaker/Fuse tripping on Inrush (> 10x Nominal Current). Or cheap Mean Well AC/DC PSUs or other "cheap" (reasonably Priced) Manufacturers for 25-300W PSUs. Same for your Phone Charger or Laptop AC Adapter for that Matter, especially at low Load. Tell me about your Power Factor there. And don't mind an Inverter-based Heatpump, those do not even have Active PFC, here in Europe most are just standard 3ph Diode Bridge Rectifiers (although PF for 3ph Systems is already much Better).
Also remember ... Power Factor != cos_phi. Power Factor is cos_phi multiplied by the THD !
For ATX Power Supplies, while there is usually Passive PFC (mostly on old Designs - filters are Expensive and Bulky after all) or Active PFC, the question is: at which AC Voltage you are Operating and at which Load you are Operating.
I just gave it a try right now to prove my Point to you. Seasonic SSR-1000PD Active PFC F3 PRIME ULTRA PLATINUM 1000W PSU. 80+ Platinum. 230 VAC. Load 30-40W measured on AC side (3-4% or Rated Power) when AMD 5950x is idling on low Power, same for the GPU. The Kill-A-Watt meter is fluctuating between 0.37 and 1.00 Power Factor, oscillating quite a lot whenever the Load (slightly) Changes. Simply because it's very difficult to take a sinusoidal input current (and precisely measure / calculate the required Current) at such low load and there is not enough discharge of the High-Voltage side DC-Link / Capacitors in order to do that. Instead it's probably periodically "pumping" some current in order to recharge the Capacitor.
(It would probably be better to use something like an Eastron SDM 120 or even Eastron SDM 630 or just put a scope with Differential Voltage Probe and Current Probe to get a better Measurement though)
There is a PFC Circuit, yes, but the sizing of it is (probably) made on the Assumption that you are at least at 20%+ Load or something like that.
Then, what happens if (your PFC Transistor Switching Frequency being constant), your Input Current is so small (compared to the Design Operating Point) that you go into Discontinuous Conduction mode ?
Take a Look here to see the
Waveforms or
even more of them. But if now the PFC Ripple becomes large compared to the average Input Current required by the Load, then you hit Discontinuous Conduction Mode (the border case is described in the Figure on the Right side in the 2nd Link). And you obviously do NOT want the PFC to increase the Switching Frequency at low Load, that would thrash the Efficiency completely !
115 VAC is easier than 230 VAC to always boost (you definitively do NOT want to boost too much, otherwise for 230 VAC you go too high) so the Power Factor is usually better in 115 VAC of course (also for passive PFC for that matter).
But at low Load (whatever "low" means depends on the Power Supply and many Design Choices), do NOT expect the Power Factor to be very good. Same for the Efficiency for that Matter.
The Ripple Current is, depending on the design, 10-20% of the Nominal Current (depending on several compromises: size of Inductor/Filter, choice of Switching Frequency, target efficiency, etc), so if you are at "low" Load you are not really "following" a Sinusoid. It's more similar to a passive PFC at that point. Also because the voltage on the High voltage DC Capacitor doesn't "drop" as expected since the load is so small ... so the PFC Controller will not require (or not be able to demand) higher AC current.
Above say 20% Load I'd expect the Power Factor to be relatively good (> 0.90 or even > 0.95).
EDIT 1: the "Energy Star" Initiative for Instance requires: "True power factor of 0.9 or greater
at 100% of rated load." That's a funny one, because you are NEVER going to fully load your PSU
.
EDIT 2: The
official 80+ Certification States that:
- PFC ≥ 0.90 for 80+ Gold at >= 50% Load
- PFC ≥ 0.95 for 80+ Platinum at >= 50% Load
80+ Titanium is even more Strict in that Regards: PFC ≥ 0.95 at >= 20% Load.
But yeah, nothing Required below 20% Load ...
