HP Z420 Not Booting up Directly (Weird case)

[EggKnight]

Hi, I am facing a weird problem with my HP Z420. My computer doesn't start the first time I click the power button, it only gives loud fans and no display. At first, when I click the power button, nothing happens, no display but after a few seconds, like 25 seconds, the fans start making a loud noise nonstop. 
So, I have to force the shutdown by pressing the power button until everything is shut, and then when I click the power button the second time the computer boots up and works fine. Any ideas on how to fix this?
Config:
Xeon E5-1650 0 3.2GHz
6 Cores,12 Threads, 12 MB Intel® Smart Cache

16GB RAM

500GB SSD

500GB HD
Nvidia Quadro 600 1GB

Anyway to fix this problem? Thanks!

[DGroves]

is the system directly connected to the outlet or does it connect through a power strip/UPS or similar if so remove and directly connect to power outlet

once connected directly to power outlet does the issue only happen after sitting for a while IE- power off wait 2 hr or more and it happens or can you power off wait 30 sec and power on and have the issue ?

if either are true replace power supply

[EggKnight]

The system was connected to a power strip, so I removed it and used an outlet directly but the problem is still here sadly.
I guess it may be a PSU issue here, as I tried a lot of other solutions but none of them seem to work. 

Waiting for PSU to arrive to test it out. Could this issue be from something else?

Thanks for the assistance, I appreciate it!

[EggKnight]

Hello again,

So, I tried a second PSU, the problem seemed to be gone for a few hours, but then is back again. I don't know what to try anymore. 

[SDH]

I vote for a new used Z420 version 2 motherboard off eBay. We can help ensure you know exactly what to look for to get a v2.

CPU... upgrade to a v2 CPU... E5-1660 v2 maybe, recycled.

About 45.00 for item 1 and 20.00-30.00 USD for item two. Assuming you already have memory that is as fast as your new hexacore processor (1866MHz) you'll be happy again.

By the way you still can buy that same processor new from Intel for about $1100.00 USD including tax and shipping.

[EggKnight]

So I guess since you're mentioning buying another motherboard, the one I have now can't be repaired?

And is a CPU upgrade necessary too?

[SDH]

My advice is to buy a used version 2 motherboard. Those can run both the original (version 1) and the v2 processors that HP certified for use. A v1 motherboard cannot reliably run v2 processors. You don't say if your motherboard is a v1 or a v2. If you snap a picture of the barcode label on the motherboard (by the motherboard battery) I can let you know just from that. If you can get into BIOS and see your "boot block date" that is another way to know. If you use a free utility like CPUz to probe your processor and see it is "E5-1650 v2" then you have a v2 motherboard. 

The HP-approved v2 processors can be seen in a recent Z420 QuickSpecs... I'll post a PDF copy here shortly. We have upgraded a bunch of our Z420 v2 workstations with the E5-1660 v2 processors. They have only one Spec Code (SR1AP) and I use that to search eBay for those... about $30.00 USD including shipping right now. That is a good price. Intel's recommended retail price for a new one is $1083.00. I like to recycle instead.

[SDH]

No... too expensive to repair and to try and find the site of the component partial failure would be very difficult. We don't really know even if it is the motherboard at this point. I'm just making an educated guess.

Boot Block Date: 2011 was the year of the BBD of the v1s; 2013 was the year for the v2s.

No you don't need to buy another processor unless you want to... I don't think it is a processor issue.

EDIT: attached is the last version of the Z420 QuickSpecs I've ever found... that has good info on the v1 and v2 processors.