Why does my Asus KGPE-D16 turn on CPU fans as soon as case SUPERMICRO CSE-835TQ-R920B is plugged in? Oh, and it won't ever turn the fans off.

im afraid i will ask you to take pictures (or write them down here) of all settings on the BIOS and post them here in order to help you. This type of behabior its not easy to determine with this combination since can be cause by a WOL NIC setting or s1 to s5 power state.

It will probably take 30 pics, or a lot of writing, I'll do whatever it takes until I lose my mind and refund the case. I have set the bios to defaults, I have disabled all kinds of CPU and power settings, and set them back to default.
I do understand the WOL settings and can turn them all off. I have seen the power state settings and have never changed them, right now ACPI is disabled, I thought that would stop all this nonsense. no difference. I'll change the p state to s5 and see what happens.

You really want ALL the settings?  or just certain sections?

well power related section, and security section.

OK I just made sure the "resume on" settings (not WOL) were all off, they were, I have only s1 and s3 and auto for choices for the power state settings, I tried them all no difference. Also the power failure setting is Power Off (so it should NOT power on when plugged in, it does not boot up but it does power on the PCU and case fans.)

I'll get those pics of the bios now. I can't help but wonder what this case's PSU is 'listening' to, or ignoring, that makes all the fans stay on. My instinct says that the PSU has some new fancy firmware in it, something to do with BMC or ACPI or the ASMB4, and few enough people use it, fewer yet have seen it error like this.

The First board I did not play with any of that and it had this same problem. To try something different I started this board out fully populated with the SMB wire from the PSU plugged in, and the ASMB4 board inserted, and it had the same problem out of box.

OH, and one more thing, trying to follow the manual on upgrading the firmware for the ASMB4 board fails, I do not have it plugged in now, but I did have it  on this board. I did not plug it in the previous board at all and it had the same fan power behavior. Maybe the previous board would have failed firmware upgrade as well, maybe they DO both have the same problem and both should RMA, If I could walk into a store and buy a new Asus server board I'd use it for troubleshooting, which is probably one of the reasons why they are not sold on retail shelves to begin with, to avoid returns from both the people who don't know what they are doing and those who need to prove to themselves that they do.

It's getting late I'm starting to vent, I'll do the bios pictures tomorrow, maybe.
I do not want to appear uncooperative, but I've had one meal in the last....
yeah see ya tomorrow.

Since you don't have the issue with a different power supply, it seems likely this is related to the SMBus control features of the redundant PSU, which has  PMBus and I2C control capability.    Look in the BIOS for any SMBus settings; and be sure your power settings are set to use S3 sleep - not S1.

>>  My CPU fans power on as soon as power supplies(redundant) are plugged in.  <<   this means 12V is present - which also means the PS is already turned ON
are you sure you have not shorted the mobo to any standoffs when mounting the mobo? (that explains also that you have it with 2 same mobo's) ?
you need to take the mobo out, and verify that each mounting stud corresponds with a screw hole in the mobo

It's very unlikely this is a motherboard shorting issue, since the problem does NOT occur with a different PSU.    It could, of course, be a problem with the ATX control line in the cable to the PSU -- double-check the ATX connector and be sure all of the pins are seated correctly in the 24-pin connector.

Thanks Gary you got me thinking, I'm gonna do a pin 16 short test, haven't thought about that in a decade. Actually use a PSU tester, then call SuperMicro and Asus back again.

what isa  " I'm gonna do a pin 16 short test" ?

nobus => Clearly this refers to checking for a short in the power on line of the 24-pin connector from the PSU.

http://pinouts.ru/Power/atx_v2_pinout.shtml

that's exactly why i don't understand " a pin 16 short test"

So unplugged the motherboard and shorted pin 16 of the PSU to ground, with no load it starts but does not stay on. This is often normal but I will tell SuperMicro, I also used an Antec PSU tester, which does provide some load and tests the voltages, it tests fine, comes on when plugged in and all green lights=ok.
 I tested the motherboard power socket pin 16 to ground and have no continuity, which is normal.
Then, with the PSU plugged in I plugged it into the motherboard, the PSU comes on immediately, this is NOT supposed to happen. Somehow it seems it does not need anything but a load to turn it on?
Yet it does not do this with different model motherboard.

TruTekTom => Note that if there's an issue with this, it will be in the cable from the PSU;  NOT on the ATX connector on the motherboard (since you don't have the problem when using a different PSU).

I'd use a multimeter to check for a short between the pin 16 wire and all of the surrounding grounds (pins 15, 17, 18, and 19 are all grounds).    If you find continuity with any of these, then that's the problem.   If that's the case, SuperMicro should replace the power supply.

Gary, thanks for the detail!
I only checked 15 and 16, figuring any/all ground would do, but if you are right and this issue is inside the cable of the PSU somehow, then I should test them all.
BUT this PSU works with other boards. Again bringing me to the idea there is some defect in the 2 boards I was lucky enough to get, or an incompatibility  issue.
This project killed my Monday I have to fix a printer, and other stuff today to actually make some money. I'll be getting back to this in the afternoon. Hopefully after some more info from vendors.

Definitely strange that the PSU works fine with a different motherboard.   You'd already noted that the motherboard works fine with a different PSU => so now you have a real Catch-22 situation.    You've likely already done this, but just in case, look VERY carefully at the pins in the ATX connector cable from the PSU and be sure they're all pushed in firmly.   This may be a situation where that specific pin isn't being properly seated with your motherboard, but the pins on another board you tried are fractionally longer and made the contact.

You've already tried 2 motherboards with identical results ... at this point if it's not a cable continuity issue (e.g. loose pin) I'd see if SuperMicro will replace the PSU.

nobus => r.e. "... that's exactly why i don't understand " a pin 16 short test" " ==> Testing for a short.    It's not referring to time (as in a short time).    Is that what you're confused about?

I have mention about bios settings just to make of certain things.you don't have to do it. just to know what do they told you at support? were they amazed of this behavior?

So the current status is:
Marck911: wol/resume or p-state may still be part of the problem, but I'll dismiss that for the moment (may readdress later though) as it has been my experiance that new stuff out of the box pretty much works with default settings. If I came upon a new customer with these complaints I'd think like you that some setting is wrong, or a strange combination.

In my 2014-07-14 at 21:45:45 comments back to Marck911, I said I failed when attempting to upgrade the firmware for the ASMB4, I was worried it may be a "tell" or clue of the actual problem. I tried again today and it worked, the firmware upgraded and now I can get into it all the extra bios settings, and see the reports and logs. I am hoping that it may expose another clue as it monitors temperatures and voltages and many other things that just may be helpful.

After this change I of course ran through the tests again and there was no change. As soon as the cord is plugged in the power, the CPU and case fans come on. They do not shut off ever, they do change speed up and down appropriately, but never go off. I also tested with different settings for p-state power cap, and fan speed modes and try disabling all kinds of features, rebooting, seeing no difference setting back to default.

garycase: great suggestions all, I checked the actual physical characteristics of the sockets, pins and wires, I did an additional check for continutity and could not find anything other that expected, all the grounds meet, and nothing else meets ground.

I called SuperMicro back and ran them through the facts, I am now going to RMA the power distributor, which is the junction between the two PSUs and the motherboard.

I'll play with the current system a few times to see if I can get anything interesting to show up in a log.

I need to remind myself of the 2004 era when leaky capacitors caused all kinds of unexplainable disturbances, and that perhaps some board level componant in the power supply system is just unhappy with this motherboard but ok with others. If something like this ends up being the case, then we would never logic it out, just figure out what to replace. I hate those puzzles that remind us that divorce is sometimes the only answer.

I'll let you know what happens after replacing the disrtibutor.

Gary - tx for the update - but i got the meaning  from the rest of the posts (pin 16)

The new Power Distributor solved the problem, my diagnosis is that one or more components on the board was outside of some tolerance or another, enough to get things confused.

Gary, Thanks for going down this path with me your questions and focus helped narrow this down.