Mac Pro 3,1 – Dark screen, then freezing, then Fans go maximum, Red RAM lights flash on boot

If its a heat sensor related to the PCIe port where the Graphic card resides - this would make sense as it is not using the full resolution of the graphics card so heating would take longer. I believe I will replace the mother board – why not – tried everything else – once I get a spare few hours – the take apart on these MPs is time consuming – Perhaps a futile effort for an aging Mac Pro but must be done. Our studio runs on mostly Mac Pros 5,1s and 6,1s all still going strong. We even have a MP 1,1 Filemaker server that has run 24/7 for 15 years in our server room – Never crashes! What work horses these machines are!

Thank you, just trying to eliminate all possibilities to come to a conclusion. Do you have any recommends on trouble shooting the dark screen crashes. I call them that because the the screen goes to black and and then the fans slowly begin to increase to maximum speed. I can always boot up and get through the logon screen. Once I begin any diagnostics or installations it will crash. It is letting me download software and some general tasks. always eventually crashes.

I went to the standard GeForce GT 120 512MB to trouble shoot - It had a 5770 flashed card in it originally. I also tried a working 5870 Mac version which also had the same issue. I tried a Nvidia GeForce GT 640 2GB card that runs without power cables - same results. All cards were tested in both 16x PCI slots. I originally felt this was going to be a quick fix as I assumed the that original 5770 was going bad and with the black screens it felt like a video issue.

System uptime in nanoseconds: 46434472112

last loaded kext at 46196157683: com.apple.driver.AppleHWSensor 1.9.5d0 (addr 0xffffff7f82749000, size 36864)

loaded kexts:

com.apple.driver.AppleHWSensor 1.9.5d0

com.apple.driver.AppleGraphicsDevicePolicy 3.12.7

com.apple.filesystems.autofs 3.0

com.apple.driver.AppleMCCSControl 1.2.13

com.apple.Dont_Steal_Mac_OS_X 7.0.0

com.apple.driver.ACPI_SMC_PlatformPlugin 1.0.0

com.apple.driver.AppleLPC 3.1

com.apple.nvidia.NVDAStartup 10.1.0

com.apple.driver.AppleUSBDisplays 378

com.apple.driver.AppleIntel8254XEthernet 3.1.4b1

com.apple.iokit.IOAHCIBlockStorage 2.8.5

com.apple.driver.AppleFileSystemDriver 3.0.1

com.apple.driver.AirPort.Brcm4331 800.21.30

com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1

com.apple.driver.AppleFWOHCI 5.5.4

com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0

com.apple.BootCache 38

com.apple.driver.usb.AppleUSBEHCIPCI 1.0.1

com.apple.driver.usb.AppleUSBUHCIPCI 1.0.1

com.apple.driver.AppleAHCIPort 3.1.8

com.apple.driver.AppleIntelPIIXATA 2.5.1

com.apple.driver.AppleACPIButtons 4.0

com.apple.driver.AppleRTC 2.0

com.apple.driver.AppleHPET 1.8

com.apple.driver.AppleSMBIOS 2.1

com.apple.driver.AppleACPIEC 4.0

com.apple.driver.AppleAPIC 1.7

com.apple.driver.AppleIntelCPUPowerManagementClient 218.0.0

com.apple.nke.applicationfirewall 163

com.apple.security.quarantine 3

com.apple.security.TMSafetyNet 8

com.apple.driver.AppleIntelCPUPowerManagement 218.0.0

com.apple.driver.AppleGraphicsControl 3.12.9

com.apple.kext.triggers 1.0

com.apple.driver.AppleSMBusController 1.0.14d1

com.apple.iokit.IOSurface 108.3.2

com.apple.nvidia.driver.NVDAGK100Hal 10.1.0

com.apple.nvidia.driver.NVDAResman 10.1.0

com.apple.AppleGraphicsDeviceControl 3.12.9

com.apple.iokit.IOBluetoothFamily 4.4.6f4

com.apple.iokit.IONDRVSupport 2.4.1

com.apple.iokit.IOGraphicsFamily 2.4.1

com.apple.driver.AppleSMC 3.1.9

com.apple.driver.IOPlatformPluginLegacy 1.0.0

com.apple.driver.AppleSMBusPCI 1.0.14d1

com.apple.driver.IOPlatformPluginFamily 6.0.0d7

com.apple.iokit.IOSCSIArchitectureModelFamily 3.7.7

com.apple.driver.AppleUSBHIDMouse 185.3

com.apple.driver.AppleHIDMouse 185.3

com.apple.driver.AppleHIDKeyboard 181

com.apple.driver.usb.IOUSBHostHIDDevice 1.0.1

com.apple.driver.AppleUSBComposite 900.4.1

com.apple.iokit.IOUSBHIDDriver 900.4.1

com.apple.iokit.IOUSBHIDDriverPM 900.4.1

com.apple.driver.usb.cdc 5.0.0

com.apple.driver.usb.networking 5.0.0

com.apple.driver.usb.AppleUSBHostCompositeDevice 1.0.1

com.apple.driver.usb.AppleUSBHub 1.0.1

com.apple.driver.AppleXsanScheme 3

com.apple.driver.AppleUSBMergeNub 900.4.1

com.apple.iokit.IO80211Family 1110.26

com.apple.driver.corecapture 1.0.4

com.apple.iokit.IOFireWireFamily 4.6.1

com.apple.iokit.IONetworkingFamily 3.2

com.apple.driver.usb.AppleUSBUHCI 1.0.1

com.apple.driver.usb.AppleUSBEHCI 1.0.1

com.apple.iokit.IOAHCIFamily 2.8.1

com.apple.iokit.IOATAFamily 2.5.3

com.apple.iokit.IOUSBFamily 900.4.1

com.apple.iokit.IOUSBHostFamily 1.0.1

com.apple.driver.AppleUSBHostMergeProperties 1.0.1

com.apple.driver.AppleEFINVRAM 2.0

com.apple.iokit.IOHIDFamily 2.0.0

com.apple.driver.AppleEFIRuntime 2.0

com.apple.iokit.IOSMBusFamily 1.1

com.apple.security.sandbox 300.0

com.apple.kext.AppleMatch 1.0.0d1

com.apple.driver.AppleKeyStore 2

com.apple.driver.AppleMobileFileIntegrity 1.0.5

com.apple.driver.AppleCredentialManager 1.0

com.apple.driver.DiskImages 417.4

com.apple.iokit.IOStorageFamily 2.1

com.apple.iokit.IOReportFamily 31

com.apple.driver.AppleFDEKeyStore 28.30

com.apple.driver.AppleACPIPlatform 4.0

com.apple.iokit.IOPCIFamily 2.9

com.apple.iokit.IOACPIFamily 1.4

com.apple.kec.pthread 1

com.apple.kec.corecrypto 1.0

The curious part of this issue for me is that 'safe mode' allows me do run diagnostics and things that I can't run with the full boot. Removing auto login items helped a bit. Always eventually freezes after the screen goes black. Also, as I mentioned I removed all externals and internal components to zero in on potential hardware issues - this helped a bit but always resulted in the eventual black screen freeze. I did change the power supply - this also delayed freezing but still we had the eventual freeze event.

My question is: If its a hardware issue why is the 'safe boot' effecting the freeze event so dramatically?

It hadn't been generating any new panic reports for the last few crashes. The nvidia and dropbox reference in the panic reports on start up crashes have been noted so far and then care of. Let me see what I can find.