HP Z620 has full fan speed and no display

[Lester13]

My HP Z620 has full fan speed and no display when I start it up I have tried leaving it for a couple minutes but it results in no change.

[Brian1965]

Are there any beeps or flashing LED power button? Is the power button staying a steady blue colour when switched on? Try removing all USB devices, except for the keyboard/mouse.

I would try the following first;

1. Remove the power lead from the Z620

2. Press and hold the power button on the Z620 for at least 15 seconds

3. Remove the side panel and replace the CMOS battery on the motherboard

4. Press and hold the CMOS reset button for 10 seconds (next to PCI slot 6 on the motherboard)

5. Re-insert the power lead and switch on the Z620

6. Check that the PSU POST test passes - see here (chapter 4)

7. Press F10 to enter the BIOS and check settings

[Lester13]

How would I remove the power lead I have already replaced the CMOS battery and power supply with no change in the start of the computer.

[Brian1965]

Just to clarify "My HP Z620 has full fan speed and no display when I start it up" . . .

1. Are you saying your computer was working perfectly fine for weeks/months, then suddenly and without warning, failed to boot? (i.e. You did not update or modify the BIOS prior to this problem).

2. Have you recently changed or added any new hardware? i.e. HDD/SSD's, RAM, GPU, etc.

3. Has the computer been re-located recently? (i.e. moved from one room to another?)

4. You mention you changed the battery, did you perform the CMOS reset as instructed?

5. Does the power button stay a steady blue colour when you switch on?

6. Have you tried leaving the computer switched on [edit - just re-read your previous post], (with the fans running at full speed), for at least 3 to 4 minutes? Is there any change in the colour of the power light, or does it flash?

7. What fault finding have you performed so far? e.g. Have you removed and re-seated;- all DIMM modules, PCI cards, and checked all internal connectors are fully seated? If your primary GPU requires auxilliary PCI power, is/are the auxilliary power lead(s) plugged in?

8. Do you have another GPU card you can use for testing? 

[Lester13]

 found this PC in my office with just the cpu with the heat sink I put a stick of ram and a GPU in and it resulted in this error. I also reset the bios using the button located on the motherboard.  When I turn it on the blue light is constant with no beeping error even when it is on for a long period.  I replaced my ram, power supply , cmos battery, and  GPU and I still has all the same problems. I also tried removing the GPU and tried to turn on the system but I still had the same problem meaning the problem might not be GPU related. 

[Brian1965]

It sounds like the motherboard is either faulty, or has a corrupted BIOS, since the computer is not even entering the POST (Power-On-Self-Test) stage.

My next suggestion was going to be testing the system in it's bare bones configuration, or trying another GPU card, but it looks like you have already tried these.

I think your final hope may be trying to perform the BIOS Crisis Recovery procedure. SDH has written an excellent post on this procedure.  

[SDH]

A small added bit of info:

You've worked hard on this project, clearly. Don't give up. You can always buy a used HP Z620 motherboard to transplant in. For example, search eBay for Z620 motherboard or even filter for:  618264-002, price and shipping lowest. The pic below is from an ad today for that motherboard at 40.00 USD shipping included.

The barcode label is frequently shown in the eBay Z620 motherboard pictures. You want a "version 2" motherboard, and the key number is on the right-hand side of the label. You must be very clear with the seller that they must send one with that number shown above. The ones on the left-hand side have to do with whether the motherboard has been "branded" in its firmware for "No DPK" (No Digital Product Key) or branded for a Windows DPK. W7 and W8 HP licensing of these workstations can still be upgraded to W10 (and W11) without any added cost. "No DPK" means no licensing, hence a Linux install for all practical purposes. There are ways to take a Linux-branded motherboard to W7Pro64, and thereafter W10Pro64 (or even to W11 using the excellent method referenced by Paul Tikkanen here in the forum).

Long story short... It is not a bad project to swap in a new used Z620 motherboard, about 30 minutes if you've done one before. Budget an hour otherwise.