Pavilion 595-p0084 won't boot up

[BLuke]

Computer shuts down 1-5 seconds after powered on. No changes to hardware or software made in several months.  Removed all components attached to the motherboard except the CPU and changed the CMOS battery. When powered on the fans spin up and the LED behind the power switch flashes (& beeps) 3 long pulses followed by 2 short ones. The light is purple. Added back the WLAN card, same story. Add back the SSD (M.2), same story.

Add the RAM back and it shuts down in the 1 - 5 sec. range. Swapped DIMMs, no diff. Tried with only 1 DIMM, no diff, Installed the same DIMM in other slot, no diff. Repeated with the other DIMM in each slot, no diff.  Are the DIMM cards bad?

[Bill_To]

Greetings @BLuke 

Welcome to the HP Forum.

It would be very unusual to see two memory modules fail at the same time.

But the 3:2 BIOS error code you are seeing at startup points to bad memory.

You have done the recommended troubleshooting steps to isolate the bad memory module. But both memory modules are providing the same startup error code when individually installed in all memory slots.

I'm sorry but I have to ask if you are ensuring the memory modules are fully seated in the memory slot?

Other causes could be MB traces from both memory slots to the CPU. Or both memory slots (channels) have failed .

The other option I can think of would be the CPU memory controller. This would kill both memory channels.

But CPU failure would not typically provide a BIOS startup error code. Because the CPU is cooked (there would be no POST without CPU function).

So, you should not get the startup error code if: the CPU or the MB has failed.

I would try a third, known good and compatible, stick of RAM to see how it goes. It looks like it could be : a CPU or MB problem if a third stick of RAM fails.

You PC problem is a head scratcher??

Regards

[BLuke]

I also thought it would be a very low probability that both DIMMs would fail at the same time, which is why I posted this. Yes, I'm sure the DIMMs were seated and latched in.

I obtained fresh new DIMMs and the results were the same - The machine shuts down after about 3-4 seconds and without the DIMMs installed I get the 3 long beeps/pulses on the LED followed by 2 short beeps/pulses.

So how do I test for a bad CPU memory controller without the machine running? Is it a separate chip or integrated in the CPU on this machine?

[Bill_To]

Greetings @BLuke 

Did you verify the new memory modules are compatible with the HP MB? And did you try each memory module, one at a time, in each memory slot?

I don't know.

Did you ever try onboard graphics if your PC's MB rear I/O supports video out (VGA, DVI, or HDMI)? Or try a different discrete graphics card if possible.

Yes, the memory controller is embedded in the CPU. I can't relate the startup symptom to a failing CPU memory controller because you are getting the 3:2 memory error at startup when no memory is installed in the MB.

Does your PC shutdown when no memory is installed in the MB?

And it's possible the HP power supply might have a problem. Or since the PC shuts down there could also be a different component power problem causing the power supply to shut down.

Do you have to disconnect/reconnect the PC from/to AC power after a shutdown in order to restart the PC again? If yes, this would indicate the power supply protection circuits are doing their job.

The HP 595 series PCs have been around for a good while. Components tend to fail as time passes.

Regards

[BLuke]

Responses to your questions:

1. Did you verify the new memory modules are compatible with the HP MB? Yes
2. And did you try each memory module, one at a time, in each memory slot? Yes
3. Did you ever try onboard graphics if your PC's MB rear I/O supports video out (VGA, DVI, or HDMI)? Or try a different discrete graphics card if possible. No, and I'm not sure what you mean by try? When the problem 1st appeared it was connected to two (2) 24" monitors, 1 via HDMI & the other via the VGA port. 
4. Does your PC shutdown when no memory is installed in the MB? No
5. Do you have to disconnect/reconnect the PC from/to AC power after a shutdown in order to restart the PC again? NO, pressing the power button results in the fans spinning up.  If yes, this would indicate the power supply protection circuits are doing their job.
6. The HP 595 series PCs have been around for a good while. Components tend to fail as time passes. Understood.
7. And it's possible the HP power supply might have a problem. I have an older PS that I was going to swap but the connectors are different. I will try to get a new one for elimination/confirmation of that component as a cause
8. Or since the PC shuts down there could also be a different component power problem causing the power supply to shut down. Any way to further isolate those potential components?

[Bill_To]

Greetings @BLuke 

Thanks for the detailed response.

Have you tried only connecting a monitor to the PC? No USB peripherals (keyboard, mouse, and other USB devices).

You've stripped down the internal components to the core stuff required to get a good POST. This would be:

1. Power supply

2. RAM

3. Graphics card

4. CPU

5. MB

3. You could then connect a monitor to the MB if your MB and CPU  support video out via the MB I/O shield (VGA, or DVI, or HDMI) located where you see rear: USB ports and the Ethernet port.

You'll have to remove the existing discrete graphics card to use onboard video out.

Or install a different, known good and compatible, discrete graphics card.

7 and 8. Sadly, you would then have to swap in, one at a time, a different power supply and a different CPU.

The MB would be an item of interest if swapping in all of the above components do not correct your PC's startup/shutdown problem.

I would remove the MB from the case at this point. Then test all components (HP parts plus whatever replacement parts you have tried) outside of the case.

Swapping in all components is expensive.

I usually recommend using a local PC Tech at some point in this process unless you have the required replacement components.

Regards

[BLuke]

Follow up on the monitor & graphics card question: 

Have you tried only connecting a monitor to the PC? No USB peripherals (keyboard, mouse, and other USB devices).  The machine does not have a discrete graphics card, so the only video output is the onboard video and as previously mentioned, there were 2 monitors connected, 1 via HDMI and the other via the VGA port, both go directly to the MB.  I connected the monitors 1 at a time with no RAM installed and the machine starts up and stays running, with the 3 long/2 short beeps.  With the RAM installed, it shuts down as described previously.

Regarding the BIOS 3/2 error code, it continues for 5 cycles of the 3/2 beeps and then stops. I assume that is normal.

Is the check with the monitors only connected  to put a load on the system/PSU or for loading the CPU via the on-board graphics?

I'm not opposed to taking it to a local PC Tech, except the $$ would probably cover close to half of a new version of a similar PC. Plus, I like to try to figure these things out, learn something and fix things myself (with a little help from folks like yourself).  

[Bill_To]

Greetings @BLuke 

I see. You are using onboard CPU graphics.

You would normally try onboard graphics if the PC was using a discrete graphics card installed in the PCIe x16 slot.

Or you would need to try a second discrete graphics card if the PC's CPU and MB rear I/O don't support onboard graphics.

I suggested only connecting one monitor (no USB peripherals) to verify a USB problem or a USB peripheral problem does not exist. 

A bad USB port or a flaky peripheral could cause the system to shut down.

It is challenging to troubleshoot PC problems.

But we're running out of component options to check since it looks like it's coming down to the power supply, the CPU, or the MB.

You would have to swap in each remaining component one at a time. Which means you need to have, known good, replacement components.

A PC Tech could check all your PC's other components (minus the MB and PSU) using an open air test bench: MB and power supply to isolate the faulty part.

So the HP PC would have a MB or power supply problem if all of the other components work in a test bench rig.

Regards