Mac Pro (2009) crashing about once daily

My Mac Pro from 2009 started to crash daily. Sometimes I can work one day without a crash, but on the next day it’ll freeze. It looks like a hardware issue to me, because the freezes happen in OS X 10.10 and Windows 8.1. In most cases there is no kernel panic log and the events from Console.app right before the crash are random. I didn’t change the underlying hardware, didn’t add or replace a card or something else in the Mac Pro. The crashes started to appear about a month ago. When I manage to get a panic log, it looks similar to this one:

Anonymous UUID: 688BA52E-B5A5-A6A2-9C02-AF8CD3816F7F

Thu Mar 5 09:49:00 2015

*** Panic Report ***

Machine-check capabilities: 0x0000000000001c09

family: 6 model: 26 stepping: 5 microcode: 17

signature: 0x106a5

Intel(R) Xeon(R) CPU X5550 @ 2.67GHz

9 error-reporting banks

Processor 8: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 9: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 10: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 11: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 12: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 13: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 14: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

Processor 15: IA32_MCG_STATUS: 0x0000000000000004

IA32_MC1_STATUS(0x405): 0xbe00000000400e0f

IA32_MC1_ADDR(0x406): 0x000000e1e7e1e000

IA32_MC1_MISC(0x407): 0x0000000001000000

panic(cpu 8 caller 0xffffff8009e1ae0a): "Machine Check at 0xffffff8009e14e53, registers:\n" "CR0: 0x0000000080010033, CR2: 0xffffff81cc86b000, CR3: 0x00000001ac5f0000, CR4: 0x0000000000002660\n" "RAX: 0xffffff81e9c8d000, RBX: 0xffffff804202e0f0, RCX: 0xfffffef9c0000000, RDX: 0xfffffeb9c0000000\n" "RSP: 0xffffff8217463028, RBP: 0xffffff8217463060, RSI: 0xffffff800a4bd000, RDI: 0x0000000000060e55\n" "R8: 0x0000000000000001, R9: 0xffffff8217463374, R10: 0xffffff802bddbc00, R11: 0x0000000004730000\n" "R12: 0xffffff800fc7b3d0, R13: 0x00000000002687a4, R14: 0x0000000000000000, R15: 0xffffff8011237680\n" "RFL: 0x0000000000000282, RIP: 0xffffff8009e14e53, CS: 0x0000000000000008, SS: 0x0000000000000010\n" "Error code: 0x0000000000000000\n"@/SourceCache/xnu/xnu-2782.10.72/osfmk/i386/trap_native.c: 168

Backtrace (CPU 8), Frame : Return Address

0xffffff81c9b55e90 : 0xffffff8009d2fe41

0xffffff81c9b55f10 : 0xffffff8009e1ae0a

0xffffff81c9b56070 : 0xffffff8009e36f2f

0xffffff8217463060 : 0xffffff8009d98e3c

0xffffff8217463210 : 0xffffff8009dc702e

0xffffff82174635b0 : 0xffffff8009d973e3

0xffffff8217463610 : 0xffffff800a2e6d41

0xffffff8217463730 : 0xffffff800a2e7041

0xffffff8217463760 : 0xffffff7f8c05c703

0xffffff8217463790 : 0xffffff7f8c027031

0xffffff82174637b0 : 0xffffff7f8c05b4b0

0xffffff82174637d0 : 0xffffff7f8c03fca8

0xffffff82174637f0 : 0xffffff7f8c0e8c18

0xffffff8217463810 : 0xffffff7f8c0c9773

0xffffff8217463850 : 0xffffff7f8c0c9b85

0xffffff82174638e0 : 0xffffff7f8c0c7a0c

0xffffff8217463970 : 0xffffff7f8c0c7025

0xffffff82174639d0 : 0xffffff7f8c02c149

0xffffff8217463a00 : 0xffffff7f8c0397ec

0xffffff8217463a50 : 0xffffff7f8c0c7f2b

0xffffff8217463aa0 : 0xffffff7f8c02a432

0xffffff8217463b30 : 0xffffff800a300652

0xffffff8217463b60 : 0xffffff800a301249

0xffffff8217463bc0 : 0xffffff800a2fe9c3

0xffffff8217463d00 : 0xffffff8009de4a87

0xffffff8217463e10 : 0xffffff8009d33f8c

0xffffff8217463e40 : 0xffffff8009d18a93

0xffffff8217463e90 : 0xffffff8009d293bd

0xffffff8217463f10 : 0xffffff8009e059fa

0xffffff8217463fb0 : 0xffffff8009e36ea6

Kernel Extensions in backtrace:

com.apple.iokit.IOAcceleratorFamily2(156.6)[3CD19A58-C154-33E1-8466-30BF06B8F39 B]@0xffffff7f8c026000->0xffffff7f8c092fff

dependency: com.apple.iokit.IOPCIFamily(2.9)[56AD16B5-4F29-3F74-93E7-D492B3966DE2]@0xffffff 7f8a524000

dependency: com.apple.iokit.IOGraphicsFamily(2.4.1)[619F6C9F-0461-3BA1-A75F-53BB0F87ACD3]@0 xffffff7f8ab72000

com.apple.GeForce(10.0.2)[2F110774-274B-3796-AD7B-3D26772A4942]@0xffffff7f8c0a1 000->0xffffff7f8c136fff

dependency: com.apple.iokit.IOPCIFamily(2.9)[56AD16B5-4F29-3F74-93E7-D492B3966DE2]@0xffffff 7f8a524000

dependency: com.apple.iokit.IONDRVSupport(2.4.1)[E5A48E71-70F5-3B01-81D3-C2B037BBE80A]@0xff ffff7f8abb9000

dependency: com.apple.nvidia.driver.NVDAResman(10.0.2)[EFB702DE-5458-35DF-84DA-E0FFC4DCA500 ]@0xffffff7f8ae43000

dependency: com.apple.iokit.IOGraphicsFamily(2.4.1)[619F6C9F-0461-3BA1-A75F-53BB0F87ACD3]@0 xffffff7f8ab72000

dependency: com.apple.iokit.IOAcceleratorFamily2(156.6)[3CD19A58-C154-33E1-8466-30BF06B8F39 B]@0xffffff7f8c026000

BSD process name corresponding to current thread: ReadKit

Boot args: arch=x86_64

Mac OS version:

14C109

Kernel version:

Darwin Kernel Version 14.1.0: Mon Dec 22 23:10:38 PST 2014; root:xnu-2782.10.72~2/RELEASE_X86_64

Kernel UUID: DCF5C2D5-16AE-37F5-B2BE-ED127048DFF5

Kernel slide: 0x0000000009a00000

Kernel text base: 0xffffff8009c00000

__HIB text base: 0xffffff8009b00000

System model name: MacPro5,1 (Mac-F221BEC8)

System uptime in nanoseconds: 37414576975714

last loaded kext at 34173385004982: com.apple.security.TMSafetyNet 8 (addr 0xffffff7f8ca40000, size 12288)

last unloaded kext at 34172653441773: com.apple.security.TMSafetyNet 8 (addr 0xffffff7f8ab2c000, size 8192)

loaded kexts:

com.logmein.driver.LogMeInSoundDriver 1.0.3

com.Logitech.Control Center.HID Driver 3.9.1

at.obdev.nke.LittleSnitch 4234

com.apple.security.TMSafetyNet 8

com.apple.filesystems.afpfs 11.0

com.apple.nke.asp-tcp 8.0.0

com.apple.filesystems.udf 2.5

com.apple.driver.AppleBluetoothMultitouch 85.3

com.apple.driver.AppleHWSensor 1.9.5d0

com.apple.driver.AppleTyMCEDriver 1.0.2d2

com.apple.driver.AGPM 100.15.5

com.apple.driver.AppleOSXWatchdog 1

com.apple.filesystems.ntfs 3.12

com.apple.filesystems.autofs 3.0

com.apple.driver.AppleMikeyHIDDriver 124

com.apple.driver.AppleUpstreamUserClient 3.6.1

com.apple.driver.AppleHDA 269.25

com.apple.driver.AppleMCCSControl 1.2.11

com.apple.iokit.IOUserEthernet 1.0.1

com.apple.driver.AppleMikeyDriver 269.25

com.apple.GeForceTesla 10.0.0

com.apple.GeForce 10.0.2

com.apple.iokit.IOBluetoothSerialManager 4.3.2f6

com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport 4.3.2f6

com.apple.Dont_Steal_Mac_OS_X 7.0.0

com.apple.driver.AppleLPC 1.7.3

com.apple.driver.AppleHWAccess 1

com.apple.driver.AppleHV 1

com.apple.driver.AudioAUUC 1.70

com.apple.driver.ACPI_SMC_PlatformPlugin 1.0.0

com.apple.driver.XsanFilter 404

com.apple.iokit.IOAHCIBlockStorage 2.7.0

com.apple.driver.AppleUSBDisplays 372.1

com.apple.iokit.SCSITaskUserClient 3.7.3

com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1

com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1

com.apple.BootCache 35

com.apple.driver.AppleUSBHub 705.4.2

com.apple.driver.AppleFWOHCI 5.5.2

com.apple.driver.AirPort.Brcm4331 800.20.24

com.apple.driver.Intel82574L 2.6.7b2

com.apple.driver.AppleAHCIPort 3.1.0

com.apple.driver.AppleUSBEHCI 705.4.14

com.apple.driver.AppleUSBUHCI 656.4.1

com.apple.driver.AppleRTC 2.0

com.apple.driver.AppleHPET 1.8

com.apple.driver.AppleACPIButtons 3.1

com.apple.driver.AppleSMBIOS 2.1

com.apple.driver.AppleACPIEC 3.1

com.apple.driver.AppleAPIC 1.7

com.apple.driver.AppleIntelCPUPowerManagementClient 218.0.0

com.apple.nke.applicationfirewall 161

com.apple.security.quarantine 3

com.apple.driver.AppleIntelCPUPowerManagement 218.0.0

com.apple.security.SecureRemotePassword 1.0

com.apple.driver.AppleMultitouchDriver 262.33.1

com.apple.kext.triggers 1.0

com.apple.driver.DspFuncLib 269.25

com.apple.kext.OSvKernDSPLib 1.15

com.apple.iokit.IOSurface 97

com.apple.nvidia.classic.NVDANV50HalTesla 10.0.0

com.apple.nvidia.classic.NVDAResmanTesla 10.0.0

com.apple.iokit.IOAcceleratorFamily2 156.6

com.apple.nvidia.driver.NVDAGK100Hal 10.0.2

com.apple.nvidia.driver.NVDAResman 10.0.2

com.apple.AppleGraphicsDeviceControl 3.8.6

com.apple.iokit.IOSerialFamily 11

com.apple.driver.AppleSMBusController 1.0.13d1

com.apple.iokit.IONDRVSupport 2.4.1

com.apple.iokit.IOBluetoothHostControllerUSBTransport 4.3.2f6

com.apple.driver.AppleHDAController 269.25

com.apple.iokit.IOHDAFamily 269.25

com.apple.driver.AppleSMBusPCI 1.0.12d1

com.apple.iokit.IOUSBUserClient 705.4.0

com.apple.iokit.IOFireWireIP 2.2.6

com.apple.iokit.IOGraphicsFamily 2.4.1

com.apple.driver.AppleSMC 3.1.9

com.apple.driver.IOPlatformPluginLegacy 1.0.0

com.apple.driver.IOPlatformPluginFamily 5.8.1d38

com.apple.driver.CoreStorage 471.10.6

com.apple.driver.AppleUSBMergeNub 705.4.0

com.apple.driver.AppleUSBAudio 295.23

com.apple.iokit.IOAudioFamily 203.3

com.apple.vecLib.kext 1.2.0

com.apple.iokit.IOUSBHIDDriverPM 710.4.7

com.apple.driver.IOBluetoothHIDDriver 4.3.2f6

com.apple.iokit.IOBluetoothFamily 4.3.2f6

com.apple.iokit.IOUSBHIDDriver 705.4.0

com.apple.driver.AppleUSBComposite 705.4.9

com.apple.iokit.IOSCSIMultimediaCommandsDevice 3.7.3

com.apple.iokit.IOBDStorageFamily 1.7

com.apple.iokit.IODVDStorageFamily 1.7.1

com.apple.iokit.IOCDStorageFamily 1.7.1

com.apple.iokit.IOAHCISerialATAPI 2.6.1

com.apple.iokit.IOSCSIArchitectureModelFamily 3.7.3

com.apple.iokit.IOFireWireFamily 4.5.6

com.apple.iokit.IO80211Family 710.55

com.apple.iokit.IONetworkingFamily 3.2

com.apple.iokit.IOAHCIFamily 2.7.5

com.apple.iokit.IOUSBFamily 710.4.14

com.apple.driver.AppleEFINVRAM 2.0

com.apple.driver.AppleEFIRuntime 2.0

com.apple.iokit.IOHIDFamily 2.0.0

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 396

com.apple.iokit.IOStorageFamily 2.0

com.apple.iokit.IOReportFamily 31

com.apple.driver.AppleFDEKeyStore 28.30

com.apple.driver.AppleACPIPlatform 3.1

com.apple.iokit.IOPCIFamily 2.9

com.apple.iokit.IOACPIFamily 1.4

com.apple.kec.Libm 1

com.apple.kec.pthread 1

com.apple.kec.corecrypto 1.0

Model: MacPro5,1, BootROM MP51.007F.B03, 8 processors, Quad-Core Intel Xeon, 2.66 GHz, 16 GB, SMC 1.39f5

Graphics: NVIDIA GeForce GTX 770, NVIDIA GeForce GTX 770, PCIe, 2048 MB

Graphics: NVIDIA GeForce GT 120, NVIDIA GeForce GT 120, PCIe, 512 MB

Memory Module: DIMM 1, 8 GB, DDR3 ECC, 1066 MHz, 0x014F, 0x545331474B52373256334E20202020202020

Memory Module: DIMM 5, 8 GB, DDR3 ECC, 1066 MHz, 0x014F, 0x545331474B52373256334E20202020202020

AirPort: spairport_wireless_card_type_airport_extreme (0x14E4, 0x8E), Broadcom BCM43xx 1.0 (5.106.98.100.24)

Bluetooth: Version 4.3.2f6 15235, 3 services, 27 devices, 1 incoming serial ports

Network Service: Ethernet Bond (bond0), Ethernet, bond0

Network Service: Wi-Fi, AirPort, en2

Serial ATA Device: HL-DT-ST DVD-RW GH41N, 3,58 GB

Serial ATA Device: Samsung SSD 840 PRO Series, 512,11 GB

Serial ATA Device: WDC WD6400AAKS-41H2B0, 640,14 GB

Serial ATA Device: ST31000528AS, 1 TB

Serial ATA Device: WDC WD15EADS-00R6B0, 1,5 TB

USB Device: Hub

USB Device: Xbox 360 Wireless Receiver for Windows

USB Device: USB Receiver

USB Device: Samson C03U

USB Device: Hub

USB Device: USB2.0 Hub

USB Device: daskeyboard

USB Device: Apple Cinema HD Display

USB Device: Hub

USB Device: iPhone

USB Device: Apple Cinema HD Display

USB Device: BRCM2046 Hub

USB Device: Bluetooth USB Host Controller

FireWire Device: built-in_hub, Up to 800 Mb/sec

Thunderbolt Bus:

Could this be a (rather costly) CPU fault or memory fault?