Can fans run without cpu

[High rise]

I have been buying parts as of recent to do a rebuild. I currently have a i5 2400 and I'm switching to a i5 10400f, in doing that I have to upgrade mobo, memory and psu. The 2400 that was working until a couple of hours ago. Randomly switched off and would turn on again. I checked connections. I tried installing the new psu. Nothing was working. So to check the psu's I put the new mobo in and tested both of my psu's and both resulted in the memory lighting up but nothing else. I read that fans are supposed to turn on even without a cpu.

Could I be wrong here. Or have I broken something. Any help or opinions would be greatly appreciated.

[High rise]

Just now, Benji said:

I am not entirely sure, but I had two different experiences: On my very old Intel Core 2 Duo system that left me ~10 years ago, the CPU fried itself and upon pressing the power button or just connecting the front panel pins with a screwdriver, nothing would happen. On my Acer with a Pentium B960 (mobile CPU) that I removed to scrap the laptop, the fans ramped up for multiple seconds and then shut down. I guess you'd have to try that.

I currently don't have a 10th gen Intel cpu lying around it arrives next week. I tried the screwdriver method nothing happens. When I first plug the power cord in, and then press the power button on case the ram lights up but nothing else. Do you recommend just waiting for my cpu delivery?

[Grabhanem]

I'd guess the board won't even try to boot if it doesn't recognize a CPU.

 

Also keep in mind that with a 10400F you'll need a dedicated graphics card, as its integrated graphics are disabled.

[High rise]

I would say It won't post. But if my memory is receiving power shouldnt my fans be receiving power? 

 

And im aware of graphics i have a gpu set aside.