Mac Pro 5.1 (flashed) doesn‘t boot

[Leraje]

Hello. I have a Mac Pro 4.1 (with Flash on 5.1), 64 GB of RAM and dual CPU board. Graphics is a Sapphire Radeon HD7950 Mac Edition.
Hard drives include a 500GB Samsung Evo 840 with High Sierra, a 500GB Samsung Evo 750 storage, a 500GB Samsung Evo 850 with Windows 10 Bootcamp, and a 1TB HDD for iTunes and Photo Library.

My problem: I had the CMOS battery changed today, since then he does not boot anymore.

The Mac hangs in different places in the boot screen with the loading bar.

PRAM reset nothing brought.
Cable off, wait 15 seconds, plug in and after 5 seconds turn on nothing brought.
Single-user is not going to boot.
Secured boats will not work.
Verbose Mode does not boot.

All hard drives out, PCIe-USB-3 card out, empty HDD in and try to boot from USB-stick is not.

Actually, nothing works anymore. I changed the battery back, but nothing works anymore, it always stays in the boot-screen with loading bar.

HELP!!!

Who knows advice?

 

[Synchro3]

Did you install the graphics card correctly after installing the CMOS battery? No bent pins?

 

[Leraje]

that's a good idea, I'll take a look

 

[Darmok N Jalad]

Might also check the connections on the PCIe power cables. I've never changed the CMOS battery before, but you might also check your connections in the area you worked on.

 

[Leraje]

I've just taken everything apart again and again together. All cables are plugged in correctly, all connections and contacts look ok.

I have now installed a completely empty hard drive and try to boot from a USB stick. I can select the stick while holding down the alt key, but then the loading bar remains in the middle of it.

 

[h9826790]

Did you ever setup any remote control? If yes, try remove the graphic card to see if able boot to desktop.

 

[Leraje]

I have now removed all hard drives, and suddenly, the red LED for the RAM bank 5 lights up. I changed the RAM, it's still glowing. Currently I have only occupied 1-3 with a total of 24 GB, since the MAC starts. Problem limited, now only wonders if the RAM bank or the memory itself is broken. Nevertheless thanks for your help.

 

[Darmok N Jalad]

I have now removed all hard drives, and suddenly, the red LED for the RAM bank 5 lights up. I changed the RAM, it's still glowing. Currently I have only occupied 1-3 with a total of 24 GB, since the MAC starts. Problem limited, now only wonders if the RAM bank or the memory itself is broken. Nevertheless thanks for your help.

Seems like an odd problem to run into. Maybe take a close look at that RAM slot for dirt or debris.

Not saying you did this, by my father-in-law once broke both RAM slots on his PC by trying to jam them in backwards. The system didn’t work after that, but he physically broke the slots!

 

[h9826790]

Did you upgrade the CPU?

 

[Leraje]

I have the board removed, all RAM slots completely blown out and cleaned with a slightly damp microfiber cloth inside. Leave for 5 hours and then reinstall all. And now everything is back up and running. In fact, probably only a small speck of dust was responsible for everything. Thanks to all who gave tips.