An automatic fuse keeps flipping with Mac Pro (6,1)

[Hyperboreus]

The specifications are as follows:

Mac Pro (Late 2013)
2,7 GHz 12-Core Intel Xeon E5-2697 v2
128 GB (4 × 32 GB) 1066 MHz DDR3 ECC (manufacturer: 0x80CE)
AMD FirePro D500

Flipping only occurs when the appliance is being connected to the mains (after remaining unplugged for several hours).

The UPS of a local Apple Service Center was shut down by Mac Pro as well.

After extensive testing the power supply was replaced.

On top of that a series of error messages concerning the DIMMs were displayed. These were presumably caused by anomalous clock frequency at 1066MHz (in favour of 1866MHz)?

The issue has now resumed.
(In all other respects the computer runs smooth.)

What in earth should I try next?

 

[Hyperboreus]

There is a Panic Report now:

Kernel Extensions in backtrace:
com.apple.iokit.IOBluetoothFamily(6.0.12f1)[9A07BB23-7147-3B6B-A5C0-784BDC83D48D]@0xffffff7f84061000->0xffffff7f84159fff
dependency: com.apple.iokit.IOACPIFamily(1.4)[D039545F-9B61-3B0D-8F90-CCCAE5BD7A52]@0xffffff7f82285000
dependency: com.apple.iokit.IOUSBHostFamily(1.2)[328248B8-6904-34F4-9BC4-7F94CD7EE484]@0xffffff7f822be000
dependency: com.apple.iokit.IOReportFamily(47)[5772C11C-ED28-322A-910F-874583B23101]@0xffffff7f8280b000

Any ideas?
[doublepost=1558438831][/doublepost]And a fresh observation:

Adobe PhotoShop (20.0.4) seemingly makes use of one only GPU.
An ddity?

AMD FirePro D500:

Chipset Model: AMD FirePro D500
Type: GPU
Bus: PCIe
Slot: Slot-2
PCIe Lane Width: x16
VRAM (Total): 3 GB
Vendor: AMD (0x1002)
Device ID: 0x679e
Revision ID: 0x0000
ROM Revision: 113-C3861J-687
VBIOS Version: 113-C3861LB-029
EFI Driver Version: 01.0D.687
Automatic Graphics Switching: Supported
gMux Version: 4.0.11 [3.2.8]
Metal: Supported, feature set macOS GPUFamily2 v1
Displays:
EV2736W:
Resolution: 2560x1440 (QHD/WQHD - Wide Quad High Definition)
UI Looks like: 2560 x 1440 @ 59 Hz
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Main Display: Yes
Mirror: Off
Online: Yes
Rotation: Supported
Automatically Adjust Brightness: No
Connection Type: DisplayPort
HP Z22i:
Resolution: 1080 x 1920
UI Looks like: 1080 x 1920 @ 60 Hz
Framebuffer Depth: 30-Bit Colour (ARGB2101010)
Display Serial Number: CNC3180J2Y
Mirror: Off
Online: Yes
Rotation: 90
Automatically Adjust Brightness: No
Connection Type: DisplayPort