hp elitedesk 800 g1 sff

[new2023computer]

Hello, good time I have a HP EliteDesk 800 G1 SFF main case that has no motherboard except Merlin Rev:A. After connecting to the power supply, the device turns on but does not display a picture. After a few moments, the fans start working at high speed. I downloaded many files from the site, but no change appeared. I searched the site and many friends had the same problem and they all said that no change appeared with the files they were given. If possible, please guide me.

[NonSequitur777 · Accepted solution]

@new2023computer,

Welcome to our HP Community forum!

Happy to assist you with your project, but please clarify a couple of things.  You said, quote: "has no motherboard except Merlin Rev:A". Just to check in with you, your HP EliteDesk 800 G1 SFF motherboard looks like this: https://i.ebayimg.com/images/g/UAEAAOSwgrBlo2Hd/s-l1600.webp.  Also, what processor do you have installed, what RAM module(s), and what primary (boot) drive do you use?

Kind Regards,

NonSequitur777

[new2023computer]

I am using an i5 4570 CPU and 4G 1600mH DDR3 RAM from Corsair on this motherboard.I am using an i5 4570 CPU and 4G 1600mH DDR3 RAM from Corsair on this motherboard.

[NonSequitur777]

@new2023computer,

OK, an i5-4570 is not a bad processor, but you can upgrade your processor all the way up to an i7-4790K also nicknamed the "Devils Canyon".  This CPU upgrade alone would be a very significant performance boost.

This was also my processor of choice in my HP EliteDesk 800 G1 Tower upgrade project: Solved: Upgrading an HP EliteDesk 800 G1 TWR - HP Support Community - 8851089.

Or go with an i7-4770, i7-4770S, i7-4790 or i7-4790S: you can purchase one of them for around $30 or less via eBay.

A single 4GB RAM stick is insufficient -go with at least 2x8GB, such as this very affordable ($28 & free shipping) eBay purchase option: Crucial 16GB (2x 8GB) Kit DDR3 1600MHz PC3-12800 UDIMM Desktop 240-Pin CL11 RAM | eBay.

Kind Regards,

NonSequitur777

[NonSequitur777]

@new2023computer,

But maybe I am running ahead of myself.  You said you couldn't get your PC to boot up properly. Can you get into BIOS?  Did your PC work previously?  What did you do or what changed before it developed the issue? Did you connect all the power supply's power cables: the white 4-pin "PWR CPU", the white 6-pin "PWR CMD", and the white 6-pin "PWR" -see the system board diagram: Camelot800 SFF IPSM.fm.

Kind Regards,

NonSequitur777

[new2023computer]

Hello 
Yes all cables are connected 
Now when I turn on the computer I have no image and after 1 minute the fan runs at full speed

Hello 
Yes all cables are connected 
Now when I turn on the computer I have no image and after 1 minute the fan runs at full speed

[NonSequitur777]

@new2023computer,

When an HP EliteDesk 800 G1 SFF powers on with no video output and, after about a minute, the CPU fan ramps to full speed, it usually means the system is failing very early in POST. The fan behavior happens when the BIOS cannot initialize hardware or communicate with the temperature sensors.

Here are the most common causes and the steps you can try:

1. Reseat or test the memory:

A bad or poorly seated RAM module can stop POST.

1. Power off and unplug the PC.

2. Press and hold the power button for 10 seconds (discharges the board).

3. Remove all RAM.

4. Install one RAM stick in DIMM slot 1 and try to boot.

5. Repeat with the other RAM module -if present.

6. Since you said you only got a single 4GB RAM stick, you really should try a different RAM stick.

If your motherboard is healthy, it should usually react differently when RAM is removed or swapped.

 

2. Remove any PCIe graphics card (if installed):

If a discrete GPU is present, remove it and connect the monitor to one of the onboard ports
(DisplayPort or VGA).

A failed GPU can prevent the system from posting.

 

3. Reset the CMOS:

1. Power off, disconnect AC.

2. Remove the CMOS battery.

3. Press and hold the power button for 20–30 seconds.

4. Reinstall the battery and try again.

 

4. Power supply check (less common):

If available, testing with another compatible HP SFF power supply can rule out a PSU voltage issue.

 

Most likely cause: motherboard failure:

If none of the above steps change the behavior, then the symptoms you described:

• No display

• No POST

• Fan going to maximum speed after ~60 seconds

• System powering on but never progressing

Unfortunately, this would strongly point to a failed motherboard, which is a known and not uncommon end-of-life issue on the 800 G1 SFF series.

Replacement motherboards for this model are usually inexpensive on eBay or local marketplaces if you wish to keep the system running.

Kind Regards,

NonSequitur777