XPS 8930, failure to power on after several hours off

Sure the new battery is good, and it's installed right-side-up? And did you clear BIOS settings?

1. Power off, unplug power cord from rear of PC
2. Press/hold power button for ~15 sec
3. Open case and remove motherboard battery
4. Press/hold power button for ~30 sec
5. Reinstall battery
6. Close up and connect mouse, monitor and keyboard
7. Reboot

But, if you have to press the BIST button to get PSU to power on, it sounds -to me- that the PSU has a problem...

@RoHe​ 

Yes, that is the procedure I followed and why I'm suspecting the power supply.

If you're using a power strip, surge protector, or UPS, remove those and connect PC directly to a working wall outlet.

Otherwise, it may be time to try a new PSU. It may pass the BIST, but fail under load when everything is connected .

@RoHe​ 

I thought about that, but it doesn't fail on load unless several hours have passed and, even then, it's not a full load as the printers and monitors are not turned on when the computer is set to come on. The printers turn on automatically about an hour later and the monitors are turned on manually when the computer is to actually be used.

It is on a UPS, but that also keeps the router on and the router is not shutting down at all, so I know it is working. That's why I thought maybe the battery was causing the problem by not triggering the internal clock to start the computer.

But the load from a router is a lot lower than the load from a PC. So maybe try plugging PC directly into a working outlet instead of UPS as a test.

And it may take several hours to fail until after the charge on various capacitors drains in PSU and/or on motherboard.

BTW: Did you check to make sure your auto-power setting is still correct in BIOS setup?  If you replaced the coin cell battery, BIOS probably got reset to defaults so auto-power ON would be OFF...

I tested it directly from the outlet after disconnecting the power cord and then holding the power button in for 15 seconds before reconnecting the cord. It failed doing that, so I'm pretty sure the APC BackUPS 1500 is not the culprit.

I check the CMOS every time I do some of this and have reset the time to various times in testing. It does start on a timed auto start as long as the power off time is not several hours.

I'm getting pretty well convinced that it's the power supply or there is a deeper problem in the circuitry of the motherboard. If the latter, it's probably time for a new computer.

@RoHe​ Well, I ordered the 850 Watt power supply. My machine was delivered in 2017 so it may have the old 450 watt supply. I didn't check when it was open, but that may help explain the problem. It has 32 gig of memory, the GeForce video card, one UEFI 1 tb drive and one AHCI 2tb drive, not to mention a USB 4tb drive, so that may well be overworking an older 450 watt ps.

The 850 W PSU was an optional upgrade for the XPS 8930.  You can go to the Support site and enter your Service Tag (don't post it here).  When it recognizes your PC, there's a link to factory system config under the model number.  Click that and you can see what PSU came with your PC.

Post back and let us know if  the new PSU solves the problems....

I read that article some time ago, well before this problem arose. The 850 PS is the only one offered by Dell for my machine at the moment, but it was the one I intended to get if I determined the PS was at fault. I have not yet made that determination, but I do believe that it is the most likely cause and, if you read my last post, you will note that I have already ordered the 850. It should arrive sometime around the 7th and I will install it as soon as I have a chance after arrival. I, of course, will report on the success or failure of this attempt to repair.

Heads up...

Another user recently ordered the 850W PSU from Dell for XPS 8930.  They're shipping a modular PSU. The 460 W PSU is non-modular, meaning it has a permanently attached bundle of cables coming out of its case.

So you'll likely need to get a set of modular PSU cables before you install the 850 W PSU because Dell doesn't include them.

IIRC, that other user returned the Dell PSU and went looking for a non-modular PSU.  XPS 8930 should use a standard ATX PSU. So if you decide to get a non-modular one, measure the dimensions of the one that's installed now so you can find a non-modular PSU that fits in the XPS 8930 case.

@RoHe​ Thank you for that heads up. Do you know whether Dell offers the cables for sale? Those did not show up as an available replacement part. I guess I will call Dell on Monday to clarify. If the cables aren't available, the PS won't be very useful unless I can acquire them elsewhere.

Don't think they sell them, and that's why the other user returned it.  The Dell link for 850W PSU says "This power supply doesn't include any cables", but it's on the very bottom line of the 3rd PSU image, so it's not terribly obvious to the buyer.

Have a read here: What cables do you need for modular PSU and other similar sites, and then go shopping at the big sales sites.  Or consider returning the 850W PSU and buying a non-modular PSU or -at the least- a modular one that comes with all the cables.

There are threads about replacing/upgrading the PSU in XPS 8930, so you may want to read some of them. But, IIRC, many of those upgrades were with modular PSUs.

@RoHe​ Just got off of chat with the Dell sales rep and that was a bust. He tried to sell me a wall power cord. I have those up the kazoo after 35 or so years of messing with computers. He told me to call tech support on Monday. I guess we'll see.

I have ordered a new power supply from Amazon and it is supposed to arrive in two days. I will report back if that solves the problem. Based on all the testing I have done, I fully expect it to.

Thanks for all the help

Did you order a modular or non-modular PSU? 

Were you able to cancel the order from Dell or will have to do a return? 

Hope new PSU solves the problem...