URGENT: New PC won't boot - Need help!

So, I finally sat down today to put together this new build using parts I’ve been hoarding since the start of the year. I went through the whole ritual—plugging in every single cable, double-checking every component against the manual at least three times just to be safe... everything seemed perfect, but when I hit the power button, the thing just flickers to life for a split second and then immediately dies on me.
The only weird thing I noticed during that brief moment is that all the fans and lights kick on, but the CPU cooler fan stays completely dead... just sitting there motionless while everything else tries to run.

And look, I know what you're thinking, but even though I built this myself, I actually know my way around hardware. I triple-checked the compatibility of everything, so there really shouldn't be any glaring issues here. Plus, the power supply is a pretty decent 700W unit, so that should be plenty.

Anyway, here’s the full breakdown of the setup:

Motherboard: Gigabyte Z390 D
CPU: Intel i5 9600KF
Cooler: Xilence M704 RGB
RAM: Patriot Viper DDR4 16 GB 3200 MHz (2 x 8 GB)
PSU: FSP Hyper 80+ 700W
SSD: Apple 860 EVO 500 GB
GPU: NVIDIA GeForce GTX 660 2 GB

That graphics card is a bit of a relic, honestly... I just pulled it out of my old rig as a temporary fix until I can grab something newer. The plan is to pick up a GTX 1660 Ti 6 GB early this month once my paycheck actually hits my account. But since that old card works perfectly fine in my previous computer, I really don't think it's the culprit behind this mess.

Long story short, if anyone has any ideas on how to get this thing running, I'd really appreciate the help... I need to get this sorted ASAP because I actually rely on this machine for work. Thanks in advance.

The most important thing is to double-check that the 24-pin power connector is fully seated into the motherboard—make sure every single pin is actually clicked in there. Also, don't forget to check that 4 or 8-pin power cable right near the CPU socket... you want to be sure that one is snug too.

Larry Ortiz5 said:The most important thing is to double-check that the 24-pin power connector is fully seated into the motherboard—make sure every single pin is actually clicked in there. Also, don't forget to check that 4 or 8-pin power cable right near the CPU socket... you want to be sure that one is snug too.

Yeah, both of them are plugged in tight and aren't going anywhere without a fight. That was the first thing I went to check, obviously...

Maybe try pulling the RAM out and reseating it in a different slot... or, you could just take one 8GB stick out entirely and see if that does the trick—if it doesn't work, try swapping it for the other one. Sometimes RAM can be a little finicky like that, right?

... you sure there isn't some extra capacitor tucked away under the motherboard in a weird spot?
Otherwise, if the CPU voltage regulator doesn't kick in, the whole PC just shuts itself down automatically.

Maybe the PSU isn't actually delivering all the voltages and amperage it's supposed to?
It kind of reminds me of this one time I dealt with something similar just by swapping out the power supply entirely.

.. or maybe you just plugged the CPU fan into some random header meant for a case fan instead of the dedicated one

Larry Ortiz5 said:Maybe try pulling the RAM out and reseating it in a different slot... or, you could just take one 8GB stick out entirely and see if that does the trick—if it doesn't work, try swapping it for the other one. Sometimes RAM can be a little finicky like that, right?

The issue might be how those two sticks are paired.
Check the motherboard manual for the specific slot configuration. For instance, if I plugged mine into slots 1 and 2, it wouldn't even POST.
It could be the same deal here—needs to be 1 and 3, or 2 and 4.

wearymason4 said:.. or maybe you just plugged the CPU fan into some random header meant for a case fan instead of the dedicated one

I don't think that's why the PC isn't starting.
You can technically run without a fan for a bit until the processor overheats or fries itself. 🙂

@Rockstar
Grab the motherboard manual and double-check every single connector placement.
Verify the PSU is actually delivering what it should.
RAM is a frequent culprit. If the modules are older, try cleaning the contacts with an eraser.
There's also a solid chance the motherboard is just dead.