Mac Pro 5,1 - no boot up - black screen

[bwave]

I've read through many threads @MacRumors and I haven't found a solution for my specific problem yet.

My system setup:
Mac Pro 5,1 Mid-2010 Westmere
Dual Quad Core 2.4
Samsung SSD 500GB (as startup/boot disk)
16 GB RAM
3x WD 4TB Disks
Sapphire HD 7970 3GB -> It's brand new and for Mac Pro 4,1 / 5,1
Mac OS X 10.13.5

My Mac was running perfectly fine for years now and ran on the latest Mac OS 10.13.5 for some time now.
A few days ago, I shut down my Mac and tried booting it a day later. Since then both of my screens are staying black. At that time I had an older graphic card installed (the Sapphire HD 7970 is new and was installed yesterday, because my first assumption was that it might be some issue with the GPU).

When I switch on the Mac the following things happen:

1. I see two red lights flashing once for a millisecond on the left and right side of each processor
2. The SSD seems to go through the regular startup process
3. I hear the chime
4. The LED on the front panel is looking fine with a constant light blue light
5. I checked the System LEDs and I have the following:
   1. CPU A (off)
      
   2. CPU B (off)
   3. PWROK (green)
   4. 5V STBY (amber)
   5. 3.3 V (off)
   6. 1.5 V (off)
   7. 1.05 V (off)
6. The other LEDs further below show:
   1. SYS.PG (green)
   2. PLT.RS (off)
   3. RI.PG (off)
   4. EFI DONE (off)
   5. GPU OK (green)
   6. 5V (off)
   7. RSN RST (off)
7. I hope I got everything right here - but to make sure that it's correct I am attaching the picture as well
   
   
   
   
8. No matter how long I wait, the monitors are receiving a signal but are staying black
9. I switched / removed RAM (startet with 2 in slot 1 & 2, started with 4 in slot 1 - 4, started with 4 in slot 1 & 2 as well as 5 & 6
10. I removed all external devices (USB / Network / Audio)
11. I also removed all HDDs except the SSD (which is working fine connected to a MacBook Pro with an external inateck HDD reader)
12. I reinstalled OS X 10.13.5 (I am currently trying to reinstall OS X 10.13.0 from a backup)
13. I checked both monitors, cables, etc. - they are both working perfectly fine
    
14. I checked both processors, they are cooled properly, there should be no problem with overheating
15. I figured out that neither the front nor the backpanel USB / Network is constantly powered.
    Sometimes when I boot the Mac, the USB Keybord is getting power, more often it is not - independent of where I connect it. It currently is the only USB device that is connected to the Mac anyways.
16. I also reset the PRAM and SMC and also changed the battery.
17. I also switched (the old and the new) graphic card slots.

So now my question:
Does anyone have an idea what it could be or how I should proceed to figure out the problem?
Are there any LEDs that should lighten up but aren't at the moment?

I really appreciate any answer or hint that helps me solve that problem

 

[expede]

Hi!
I tried to read in this manual but you can try...

https://mega.nz/#!roMwWQRZ!DJnIqji8-i50RX_HNm5DJ49n60PRwoJ0hjNiwd5WUyE

It is the "Apple Technician Guide" and here is some;

Minimum Configuration Testing

The following procedure can help you troubleshoot a “No Power” or other startup related symptom.

The method gradually builds up the system from a minimum configuration and verifies expected behaviors at each step. This approach helps determine which modules function together. The goal is to identify which module(s) cause a symptom to recur when they are added. This method may also help you discover a loose or faulty cable or connector.

If you encounter unexpected behavior during a step, you shoul investigate the last module you re-installed. Backtrack to the previous step, remove the last installed module, and re-verify the expected behavior.

Note: Minimum configuration testing may not be practical for every repair. Refer to other troubleshooting sections in this manual for additional direction.

Take Mac Pro Down to Minimum Configuration

1. Remove the following items from the Mac Pro:

• Hard drives/solid state drives
  
  
• Optical drives
  
  
• Processor tray and processor board (containing processors, processor heatsinks, and
  
  memory)
  
  
• PCIe cards
  
  
• AirPort card
  
  
• Bluetooth card
  
  
• Battery
  
  
• PCIe fan
  
  
• Processor cage (including fans)
  
  
• Front panel board
  
  Disconnect all cables from the backplane board, except the power supply.
• 
  
• 2. Attach a known good power cord from a known good AC source to the Mac Pro.
• 
  Note: When connecting the Mac Pro to AC power, verify that the LEDs for OVTMP CPUA and OVTMP CPUB briefly flash red (less than 0.5 sec). The LEDs are located under hard drive bay 1 on the backplane board. If they do not illuminate briefly, there is an issue with either the power supply or the backplane board. Generally speaking, power supplies can be affected by issues more than other modules. If you suspect a power supply has failed,verify it in another Mac Pro (Mid 2010), if available, before replacing any modules.
  
  Note: The OVTMP CPUA and OVTMP CPUB LEDs on a properly functioning Mac Pro will also momentarily flash red immediately after the Mac Pro is disconnected from AC power.
  
  
  
• 
  
  
• 3. Press the DIAG button, and verify 5V STBY LED (amber) illuminates.
  
  Expected behavior:
  
  5V STBY LED illuminates, confirming power to the backplane board. If the LED does not illumuniate, suspect power supply or backplane board failure.
  
  4. Disconnect AC power cord. Reinstall processor cage with fans and processor board. Do not reinstall processor(s), heatsinks, or memory.
  
  Notes:
  
  • Verify no bent pins on processor connector or mating connector of processor board and backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on processor connectors, and connectors on processor board and backplane board.
    
  5. Connect AC power cord. Press the DIAG button to verify the 5V STBY LED illuminates. This is
  a verify step, as you’ve added modules since previous step.
  
  Expected behavior:
  
  5V STBY LED illuminates, confirming power to the backplane board. If the LED does not illuminate, suspect power supply or backplane board failure.
  
  6. Momentarily jump the SYS_PWR solder pads to turn ON the Mac Pro.
  
  
  
  
  
• 
  
  
• 
  
• 
  
• Expected behavior:
  
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
    
    
  • One red-colored error LED illuminates on the processor board (next to the memory slots).
    
    Notes:
    
  • The solder pads are at the same location where the power button would be.
    
    
  • To help troubleshoot processor issues, check the related CPU Error LED. See “Processor
    
    Diagnostic LEDs.”
    
  7. Press and hold the DIAG button.
  
  Expected behavior:
  
  • PSU PWROK (green), 5V STBY (amber), EFI DONE (green), GPU OK (green) LEDs illuminated
    
    
  • No startup tone
    
    
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
    
  8. Disconnect AC power cord.
  At this point, to make testing easier try powering on the computer using a known good front
  panel board, power button, and cable, instead of jumpering SYS_PWR solder pads.
  
  9. Reconnect internal speaker. Reinstall a processor and heatsink in processor A connector, and one known good and compatible Apple memory DIMM in slot 1.
  
  Notes:
  
  • The Mac Pro won’t start if you use processor B only on a dual-processor board. Use processor A connector.
    
    
  • Verify no damaged pins on DIMM or processor connectors or mating connector of processor board and backplane board.
    
    
  • Verify no damaged heatsink thermal sensor and fan connector pins or mating connector on the processor board. If there is damage, all Mac Pro fans will ramp to 100% when power ON.
    
    
  • Verify no grime or foreign debris is causing contact issues on DIMM, processor connectors, and connectors on processor board and backplane board.
    
  1. Connect AC power cord. Press the DIAG button to verify the 5V STBY LED illuminates. (This is a verification step, as you’ve added modules since previous step.)
     
     
  2. Power Mac Pro ON either by PWR_ON solder pads or front panel board.
     
  Expected behavior:
  
  • The red-colored error LED on the processor board next to the memory slots at processor A should flash once only as the Mac Pro powers on.
    
    
  • Startup tone heard (if not, reset PRAM and retest)
    
    
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
    
    Notes:
    
  • If using dual-processor board, both the LEDs next to the memory slots should flash once only.
    
    
  • You can test both processors independently using processor A connector only.
    
  12. Disconnect AC power cord. Install a known-good hard drive with a compatible/bootable Mac OS installed.
  
  Notes:
  
  • Verify no damaged SATA data or power pins on drive and mating connector on backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on SATA data or power pins on drive and mating connector on backplane board.
    
  13. Connect AC power cord. Power Mac Pro on by PWR_ON solder pads or front panel board. Expected behavior:
  
  Listen for sound of hard drive boot. If no indication of hard drive boot, try drive in another bay.
  
  Note:
  
  Shortly after boot start, verify that a red-colored LED is illuminated within the optical audio-out jack at the rear of the Mac Pro. If so, software drivers have been loaded.
  
  14. Disconnect AC power cord. Install a known good compatible PCIe graphics card into slot 1 and attach a known good display.
  Notes:
  
  • Verify no damaged PCIe pins on the video card and mating PCIe connector on backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on the video card and mating connector on backplane board.
    
  15. Connect AC power cord. Power Mac Pro ON either by PWR_ON solder pads or front panel board.
  
  Expected behavior:
  
  • Listen for sound of hard drive boot.
    
    
  • Verify good uncorrupted video on display.
    
  
  
  

/Per

 

[h9826790]

What's your original graphic card?

How you reinstall the OS without able to see anything?

 

[bwave]

What's your original graphic?

How you reinstall the OS without able to see anything?

Hi @h9826790 - I reinstalled the OS on the SSD with an USB SATA IDE HDD Docking Station from my MacBook Pro.

 

[^Tripper^]

Not that this is going to help you but... I had the EXACT same thing happen to my Mac pro a couple of weeks ago. Couldn’t figure it out. Unplugged it and left it figuring I’d get to it some time later. About a week later, plugged it in to fix it and it fired right up. No issues what so ever. It’s been working fine since then.

Yeah, I know this didn’t help, just sharing my experience.

 

[bwave]

Thanks for all the information @expede: I will definitely give that a try - I just wished I could have figured out the problem before having to dismantle all things completely.

 

[JedNZ]

And I had issues similar to this several weeks ago as well. After resetting PRAM, and doing a SMC reset (unplugging power for 20secs, plug back in and wait 10secs then power up), I resorted to holding down the power button to get into programmer mode, heard the familiar firmware long beep, shutdown by letting go the power button then pressing it again so it could power back up, and voila back in business. Goodness knows what was going on.

 

[TiggrToo]

And I had issues similar to this several weeks ago as well. After resetting PRAM, and doing a SMC reset (unplugging power for 20secs, plug back in and wait 10secs then power up), I resorted to holding down the power button to get into programmer mode, heard the familiar firmware long beep, shutdown by letting go the power button then pressing it again so it could power back up, and voila back in business. Goodness knows what was going on.

Not this is anything even remotely to do with Mac's, but...

Eons ago I had a Samsung Galaxy S3 phone that had some sort of kernel panic on startup. Tried everything any anything to get past it. Nada. Even let it totally drain the battery and waited a day. Nada. So I ended up buying a new phone.

Some months later I found the S3 in a drawer, plugged it in and, once it had received enough charge, powered it up.

Came right back up as though there'd never been anything wrong.

Beats me - I've been using 'pooters my entire life and I still don't truly grasp their nuances...

I'm sure there's a really good reason why this sort of elongated stand-down sometimes works, but I'll be darned if I know what it is.

 

[Synchro3]

A week ago my Mac Pro 4,1->5,1 did no longer POST when starting.

No red lights, fans running, but no chime. It turned out the motherboard failed.

Had to remove the processor cage and exchange the board.

Installed the old Xeon W3540 before upgrading to 5,1 firmware, glad I did not sell the old CPU.

Mac Pro now running again.





Mac Pro Technician Guide: Mac Pro (Mid 2010) - tim.id.au

- Pull out optical drive carrier (page 132)
- Pull out hard drives
- Pull out the Prozessor tray (page 135)
- Pull out all PCI cards
- Pull out the PCI fan (page 142)
- Remove a cover to to gain access to the MoBo power connector (page 150/151)
- Remove processor cage (page 165)
- Remove some cables (page 200 and following)
- Remove backplane board (page 202 and following)


Regarding upgraded Mac Pro 4,1 with 5,1 firmware with W3680/3690/X5680/5690 CPU:

The new backplane board must be a Mac Pro 4,1 board:
- Install the old CPU (lucky if you didn't sell it)
- Upgrade to the latest 4,1 firmware
- Upgrade to 5,1 firmware (Netkas forum)
- Install the new CPU

And: https://forums.macrumors.com/threads/gtx-680-power-draw.2126498/#post-26244915

 

[bwave]

Hi guys, especially @expede:
I went through almost the whole process of dismantling the Mac Pro and I realise that I might have a problem with one thing that did not occur like that before:

I am fine until step 9, when the processors, thermal connectors, etc. are attached in slot A.
Slot B seems to cause some problems but I am wondering, what it might be so I attached another image, showing one RED LED next to processor B (which wasn't there by the way at the very beginning).

 

[expede]

Hi, there!

Is it not the DIMM lights. If one is red it only could be

Replace them or remove corresponding DIMM, just to test if the lights go down. EDIT: Hmm I been thinking. You wrote that you were in step 9?! Why do your picture have more than one DIMM? There is a DIMM in slot 2 also?

/Per

 

[bwave]

Thanks for your detailed explanation.
Well, I was moving from step 9 to step 10 and mounted the other processor (after checking the single processor in Slot A) and added the other DIMMs as well. I am just wondering why that light never went on before that.

Do you by the way have any recommendations regarding buying new DIMMs for that Mac?

 

[expede]

Hello!

Did it fix the "red light"? Removing or replacing the DIMM?
Regarding new DIMMs, I bought mine from OWC (Other World Computing, www.macsales.com). Have worked for me for 4 years now without hassle.

/Per

 

[stumann]

And I had issues similar to this several weeks ago as well. After resetting PRAM, and doing a SMC reset (unplugging power for 20secs, plug back in and wait 10secs then power up), I resorted to holding down the power button to get into programmer mode, heard the familiar firmware long beep, shutdown by letting go the power button then pressing it again so it could power back up, and voila back in business. Goodness knows what was going on.

This is what worked for me! Thank you. I have a mid 2010 MP upgraded to 5,1 with a RX580 Nitro+. The upgrade to Mojave more or less worked but then with the update to 10.14.6 I got a black screen on boot. It would boot in safe mode but not otherwise. Nothing I tried worked (reset SMC, PRAM, reinstalling Mojave, cleaning out kexts, creating a new user profile, etc). Until i saw the above, rebooted and held the power button until the long beep - then it booted straight up. No idea why but happy it works.

 

[crjackson2134]

I have a mid 2010 MP upgraded to 5,1

A mid 2010 cMP is already a 5,1 since new.

 

[Jayson A]

This is what worked for me! Thank you. I have a mid 2010 MP upgraded to 5,1 with a RX580 Nitro+. The upgrade to Mojave more or less worked but then with the update to 10.14.6 I got a black screen on boot. It would boot in safe mode but not otherwise. Nothing I tried worked (reset SMC, PRAM, reinstalling Mojave, cleaning out kexts, creating a new user profile, etc). Until i saw the above, rebooted and held the power button until the long beep - then it booted straight up. No idea why but happy it works.

I have almost the same configuration. I have an RX 580 Sapphire Pulse installed and after a macOS Mojave update. I was letting it update, then a little while later, I noticed my machine was completely off, so I turned it on and then I got no picture on the screen. I forced it off and tried it again... still nothing... waited forever. Tried switching display ports and typing on the keyboard, still nothing. So finally I force it off again, unplugged it for a bit, held down the power button to release any remaining energy and then it came right up. Screen turned on and everything is fine again.

 

[richardblack]

Hi!
I tried to read in this manual but you can try...

https://mega.nz/#!roMwWQRZ!DJnIqji8-i50RX_HNm5DJ49n60PRwoJ0hjNiwd5WUyE

It is the "Apple Technician Guide" and here is some;

Minimum Configuration Testing

The following procedure can help you troubleshoot a “No Power” or other startup related symptom.

The method gradually builds up the system from a minimum configuration and verifies expected behaviors at each step. This approach helps determine which modules function together. The goal is to identify which module(s) cause a symptom to recur when they are added. This method may also help you discover a loose or faulty cable or connector.

If you encounter unexpected behavior during a step, you shoul investigate the last module you re-installed. Backtrack to the previous step, remove the last installed module, and re-verify the expected behavior.

Note: Minimum configuration testing may not be practical for every repair. Refer to other troubleshooting sections in this manual for additional direction.

Take Mac Pro Down to Minimum Configuration

1. Remove the following items from the Mac Pro:

• Hard drives/solid state drives
  
  
• Optical drives
  
  
• Processor tray and processor board (containing processors, processor heatsinks, and
  
  memory)
  
  
• PCIe cards
  
  
• AirPort card
  
  
• Bluetooth card
  
  
• Battery
  
  
• PCIe fan
  
  
• Processor cage (including fans)
  
  
• Front panel board
  
  Disconnect all cables from the backplane board, except the power supply.
• 
  
• 2. Attach a known good power cord from a known good AC source to the Mac Pro.
• 
  Note: When connecting the Mac Pro to AC power, verify that the LEDs for OVTMP CPUA and OVTMP CPUB briefly flash red (less than 0.5 sec). The LEDs are located under hard drive bay 1 on the backplane board. If they do not illuminate briefly, there is an issue with either the power supply or the backplane board. Generally speaking, power supplies can be affected by issues more than other modules. If you suspect a power supply has failed,verify it in another Mac Pro (Mid 2010), if available, before replacing any modules.
  
  Note: The OVTMP CPUA and OVTMP CPUB LEDs on a properly functioning Mac Pro will also momentarily flash red immediately after the Mac Pro is disconnected from AC power.
  
  
  
• 
  
  
• 3. Press the DIAG button, and verify 5V STBY LED (amber) illuminates.
  
  Expected behavior:
  
  5V STBY LED illuminates, confirming power to the backplane board. If the LED does not illumuniate, suspect power supply or backplane board failure.
  
  4. Disconnect AC power cord. Reinstall processor cage with fans and processor board. Do not reinstall processor(s), heatsinks, or memory.
  
  Notes:
  • Verify no bent pins on processor connector or mating connector of processor board and backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on processor connectors, and connectors on processor board and backplane board.
  5. Connect AC power cord. Press the DIAG button to verify the 5V STBY LED illuminates. This is
  a verify step, as you’ve added modules since previous step.
  
  Expected behavior:
  
  5V STBY LED illuminates, confirming power to the backplane board. If the LED does not illuminate, suspect power supply or backplane board failure.
  
  6. Momentarily jump the SYS_PWR solder pads to turn ON the Mac Pro.
  
  
  
  
  
• 
  
  
• 
  
• 
  
• Expected behavior:
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
    
    
  • One red-colored error LED illuminates on the processor board (next to the memory slots).
    
    Notes:
  • The solder pads are at the same location where the power button would be.
    
    
  • To help troubleshoot processor issues, check the related CPU Error LED. See “Processor
    
    Diagnostic LEDs.”
  7. Press and hold the DIAG button.
  
  Expected behavior:
  • PSU PWROK (green), 5V STBY (amber), EFI DONE (green), GPU OK (green) LEDs illuminated
    
    
  • No startup tone
    
    
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
  8. Disconnect AC power cord.
  At this point, to make testing easier try powering on the computer using a known good front
  panel board, power button, and cable, instead of jumpering SYS_PWR solder pads.
  
  9. Reconnect internal speaker. Reinstall a processor and heatsink in processor A connector, and one known good and compatible Apple memory DIMM in slot 1.
  
  Notes:
  • The Mac Pro won’t start if you use processor B only on a dual-processor board. Use processor A connector.
    
    
  • Verify no damaged pins on DIMM or processor connectors or mating connector of processor board and backplane board.
    
    
  • Verify no damaged heatsink thermal sensor and fan connector pins or mating connector on the processor board. If there is damage, all Mac Pro fans will ramp to 100% when power ON.
    
    
  • Verify no grime or foreign debris is causing contact issues on DIMM, processor connectors, and connectors on processor board and backplane board.
  • Connect AC power cord. Press the DIAG button to verify the 5V STBY LED illuminates. (This is a verification step, as you’ve added modules since previous step.)
    
    
  • Power Mac Pro ON either by PWR_ON solder pads or front panel board.
  • Expected behavior:
  • The red-colored error LED on the processor board next to the memory slots at processor A should flash once only as the Mac Pro powers on.
    
    
  • Startup tone heard (if not, reset PRAM and retest)
    
    
  • Front and rear processor cage fans (and PCIe fan, if installed) should spin slowly
    
    Notes:
  • If using dual-processor board, both the LEDs next to the memory slots should flash once only.
    
    
  • You can test both processors independently using processor A connector only.
  12. Disconnect AC power cord. Install a known-good hard drive with a compatible/bootable Mac OS installed.
  
  Notes:
  • Verify no damaged SATA data or power pins on drive and mating connector on backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on SATA data or power pins on drive and mating connector on backplane board.
  13. Connect AC power cord. Power Mac Pro on by PWR_ON solder pads or front panel board. Expected behavior:
  
  Listen for sound of hard drive boot. If no indication of hard drive boot, try drive in another bay.
  
  Note:
  
  Shortly after boot start, verify that a red-colored LED is illuminated within the optical audio-out jack at the rear of the Mac Pro. If so, software drivers have been loaded.
  
  14. Disconnect AC power cord. Install a known good compatible PCIe graphics card into slot 1 and attach a known good display.
  Notes:
  • Verify no damaged PCIe pins on the video card and mating PCIe connector on backplane board.
    
    
  • Verify no grime or foreign debris is causing contact issues on the video card and mating connector on backplane board.
  15. Connect AC power cord. Power Mac Pro ON either by PWR_ON solder pads or front panel board.
  
  Expected behavior:
  • Listen for sound of hard drive boot.
    
    
  • Verify good uncorrupted video on display.
  
  
  

/Per

Thank you for this. I got my mac pro mid 2010 out of storage to start using again, fired it up successfully then it just switched off. wouldn't restart. It has attempted to restart a couple of times after that but not successfully. Now, as with many others, it does not respond to the start button at all. On looking inside, it was very dusty so stripped it out completely and cleaned it all. Still no joy.
the two led lamps light for about 1\2 secs, the standby amber lamp lights on pressing diag button. Nothing when I press the start, no power light on the power button no leds inside.
I have tried without RAM, graphics card and any other peripherals with no joy. No clicks from psu or anything. I have also replaced the battery and tried resetting PRAM.
I have worked my way through the above until 4: replace processor board without processor or memory.
Mine is the single processor so do I have to remove the cooler and the processor and replace the board without them? Not sure how to do this and assume I will need to replace any heat sink compound. Any ideas?
Also, does anyone know which power supply will work with the mid 2010 (5.1 I think). I have seen it said that any from 2009 to 2012 will work.
Sorry to be asking what are probably stupid questions.
Thank you for taking the time to read this.
Richard.

 

[richardblack]

Thank you for this. I got my mac pro mid 2010 out of storage to start using again, fired it up successfully then it just switched off. wouldn't restart. It has attempted to restart a couple of times after that but not successfully. Now, as with many others, it does not respond to the start button at all. On looking inside, it was very dusty so stripped it out completely and cleaned it all. Still no joy.
the two led lamps light for about 1\2 secs, the standby amber lamp lights on pressing diag button. Nothing when I press the start, no power light on the power button no leds inside.
I have tried without RAM, graphics card and any other peripherals with no joy. No clicks from psu or anything. I have also replaced the battery and tried resetting PRAM.
I have worked my way through the above until 4: replace processor board without processor or memory.
Mine is the single processor so do I have to remove the cooler and the processor and replace the board without them? Not sure how to do this and assume I will need to replace any heat sink compound. Any ideas?
Also, does anyone know which power supply will work with the mid 2010 (5.1 I think). I have seen it said that any from 2009 to 2012 will work.
Sorry to be asking what are probably stupid questions.
Thank you for taking the time to read this.
Richard.

I have just removed the processor, replaced the processor board and tried again.
red leds flach momentarily (about 1/2 secs) and the standby led glows orange when diag button is pressed. No other leds light. Tried starting from the sys pwr pads with nothing at all. No leds no sound from the power supply.
I did find some residue on the processor board which I cleaned off carefully and thoroughly. It was spread over a noticeable area and was black and slightly greasey. The whole thing was very dusty but I have cleaned it thoroughly.
Any advice very welcome.
Thank you,
Richard.

 

[carylee2002]

Try to do a hard reset by physically unplugging the power cord away from the computer machine ( not turning off a power strip) and let stand for a minute. Also during that time to push the power button a couple of times to get rid of any residual power in the machine. Then replug the power cord into the tower. Then at startup do a NVRAM reset using Command R and Option P keys held down when at first bootup before you see the apple sign..hold it till you hear the second or third chime ( usually the louder chime ) then let go of the keys and see it that clears up any conflicts.