Strange Hardware Issue

[jonhall]

Hello,

We have been experiencing a strange problem with one of our Ubuntu boxes running version 12.10 with kernel 3.5.0-21 (64 bit). Every so often it completely freezes up and the display starts flashing colored blocks all over the screen (see attached image). This seems to occur randomly, and the only option to recover is a hard reboot (I can't even SSH into the system when this occurs). I believe it is a hardware issue, since it also occurred when running memtest from a bootable CD, so it's not specific to the Ubuntu install.

Any suggestions for troubleshooting this problem? This is a custom-built PC. The output of
dmidecode -q is below. Please let me know if any other information would be helpful.

Thanks!



BIOS Information
Vendor: American Megatrends Inc.
Version: V1.7
Release Date: 03/07/2011
Address: 0xF0000
Runtime Size: 64 kB
ROM Size: 8192 kB
Characteristics:
PCI is supported
BIOS is upgradeable
BIOS shadowing is allowed
Boot from CD is supported
Selectable boot is supported
BIOS ROM is socketed
EDD is supported
5.25"/1.2 MB floppy services are supported (int 13h)
3.5"/720 kB floppy services are supported (int 13h)
3.5"/2.88 MB floppy services are supported (int 13h)
Print screen service is supported (int 5h)
8042 keyboard services are supported (int 9h)
Serial services are supported (int 14h)
Printer services are supported (int 17h)
ACPI is supported
USB legacy is supported
BIOS boot specification is supported
Targeted content distribution is supported
UEFI is supported
BIOS Revision: 4.6

System Information
Manufacturer: MSI
Product Name: MS-7678
Version: 1.0
Serial Number: To be filled by O.E.M.
UUID: 00000000-0000-0000-0000-6C626D45DD02
Wake-up Type: Power Switch
SKU Number: To be filled by O.E.M.
Family: To be filled by O.E.M.

Base Board Information
Manufacturer: MSI
Product Name: H67MA-E45 (MS-7678)
Version: 1.0
Serial Number: To be filled by O.E.M.
Asset Tag: To be filled by O.E.M.
Features:
Board is a hosting board
Board is replaceable
Location In Chassis: To be filled by O.E.M.
Type: Motherboard

Chassis Information
Manufacturer: MSI
Type: Desktop
Lock: Not Present
Version: 1.0
Serial Number: To Be Filled By O.E.M.
Asset Tag: To Be Filled By O.E.M.
Boot-up State: Safe
Power Supply State: Safe
Thermal State: Safe
Security Status: None
OEM Information: 0x00000000
Height: Unspecified
Number Of Power Cords: 1
Contained Elements: 0
SKU Number: To be filled by O.E.M.

Cache Information
Socket Designation: Not Specified
Configuration: Enabled, Not Socketed, Level 1
Operational Mode: Varies With Memory Address
Location: Internal
Installed Size: 256 kB
Maximum Size: 256 kB
Supported SRAM Types:
Unknown
Installed SRAM Type: Unknown
Speed: Unknown
Error Correction Type: Unknown
System Type: Other
Associativity: 8-way Set-associative

Cache Information
Socket Designation: Not Specified
Configuration: Enabled, Not Socketed, Level 2
Operational Mode: Varies With Memory Address
Location: Internal
Installed Size: 1024 kB
Maximum Size: 1024 kB
Supported SRAM Types:
Unknown
Installed SRAM Type: Unknown
Speed: Unknown
Error Correction Type: Unknown
System Type: Unified
Associativity: 8-way Set-associative

Cache Information
Socket Designation: Not Specified
Configuration: Enabled, Not Socketed, Level 3
Operational Mode: Varies With Memory Address
Location: Internal
Installed Size: 6144 kB
Maximum Size: 6144 kB
Supported SRAM Types:
Unknown
Installed SRAM Type: Unknown
Speed: Unknown
Error Correction Type: Unknown
System Type: Unified
Associativity: Other

Port Connector Information
Internal Reference Designator: J1A1
Internal Connector Type: None
External Reference Designator: PS2Mouse
External Connector Type: PS/2
Port Type: Mouse Port

Port Connector Information
Internal Reference Designator: J1A1
Internal Connector Type: None
External Reference Designator: Keyboard
External Connector Type: PS/2
Port Type: Keyboard Port

Port Connector Information
Internal Reference Designator: J2A2A
Internal Connector Type: None
External Reference Designator: COM A
External Connector Type: DB-9 male
Port Type: Serial Port 16550A Compatible

Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB1
External Connector Type: Access Bus (USB)
Port Type: USB

Port Connector Information
Internal Reference Designator: J3A1
Internal Connector Type: None
External Reference Designator: USB2
External Connector Type: Access Bus (USB)
Port Type: USB

Port Connector Information
Internal Reference Designator: J5A1
Internal Connector Type: None
External Reference Designator: LAN
External Connector Type: RJ-45
Port Type: Network Port

Port Connector Information
Internal Reference Designator: J9A1 - TPM HDR
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J9C1 - PCIE DOCKING CONN
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J2B3 - CPU FAN
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J9E2 - MDC INTPSR
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J9E4 - MDC INTPSR
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J9E1 - SCAN MATRIX
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J9G1 - LPC SIDE BAND
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J8F1 - UNIFIED
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J1G6 - AC JACK
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J1G7 - BATT B
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J1H1 - BATT A
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J7H2 - SATA PWR
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J7H1 - SATA PORT2
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J7J3 - SATA PORT1
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J8J1 - SATA PORT0
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

Port Connector Information
Internal Reference Designator: J4J1 - ATX PWR
Internal Connector Type: Other
External Reference Designator: Not Specified
External Connector Type: None
Port Type: Other

System Slot Information
Designation: J6B2
Type: x16 PCI Express
Current Usage: Available
Length: Long
ID: 0
Characteristics:
3.3 V is provided
Opening is shared
PME signal is supported
Bus Address: 0000:ff:01.0

System Slot Information
Designation: J6B1
Type: x1 PCI Express
Current Usage: Available
Length: Short
ID: 1
Characteristics:
3.3 V is provided
Opening is shared
PME signal is supported
Bus Address: 0000:01:1c.0

System Slot Information
Designation: J6D1
Type: x1 PCI Express
Current Usage: Available
Length: Short
ID: 2
Characteristics:
3.3 V is provided
Opening is shared
PME signal is supported
Bus Address: 0000:ff:1c.1

System Slot Information
Designation: J7B1
Type: x1 PCI Express
Current Usage: Available
Length: Short
ID: 3
Characteristics:
3.3 V is provided
Opening is shared
PME signal is supported
Bus Address: 0000:ff:1c.2

OEM Strings
String 1: To Be Filled By O.E.M.

System Configuration Options
Option 1: To Be Filled By O.E.M.

Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 32 GB
Number Of Devices: 4

32-bit Memory Error Information
Type: OK
Granularity: Unknown
Operation: Unknown
Vendor Syndrome: Unknown
Memory Array Address: Unknown
Device Address: Unknown
Resolution: Unknown

Memory Array Mapped Address
Starting Address: 0x00000000000
Ending Address: 0x000FFFFFFFF
Range Size: 4 GB
Partition Width: 1

Memory Device
Total Width: 64 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: DIMM
Set: None
Locator: A1_DIMM0
Bank Locator: A1_BANK0
Type: DDR3
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Undefined
Serial Number: 00000000
Asset Tag: A1_AssetTagNum0
Part Number: 1333EL Series
Rank: 1
Configured Clock Speed: Unknown

32-bit Memory Error Information
Type: OK
Granularity: Unknown
Operation: Unknown
Vendor Syndrome: Unknown
Memory Array Address: Unknown
Device Address: Unknown
Resolution: Unknown

Memory Device Mapped Address
Starting Address: 0x00000000000
Ending Address: 0x0007FFFFFFF
Range Size: 2 GB
Partition Row Position: 1

Memory Device
Total Width: 64 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: A1_DIMM1
Bank Locator: A1_BANK1
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: A1_Manufacturer1
Serial Number: A1_SerNum1
Asset Tag: A1_AssetTagNum1
Part Number: Array1_PartNumber1
Rank: Unknown
Configured Clock Speed: Unknown

32-bit Memory Error Information
Type: OK
Granularity: Unknown
Operation: Unknown
Vendor Syndrome: Unknown
Memory Array Address: Unknown
Device Address: Unknown
Resolution: Unknown

Memory Device
Total Width: 64 bits
Data Width: 64 bits
Size: 2048 MB
Form Factor: DIMM
Set: None
Locator: A1_DIMM2
Bank Locator: A1_BANK2
Type: DDR3
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Undefined
Serial Number: 00000000
Asset Tag: A1_AssetTagNum2
Part Number: 1333EL Series
Rank: 1
Configured Clock Speed: 58785 MHz

32-bit Memory Error Information
Type: OK
Granularity: Unknown
Operation: Unknown
Vendor Syndrome: Unknown
Memory Array Address: Unknown
Device Address: Unknown
Resolution: Unknown

Memory Device Mapped Address
Starting Address: 0x00080000000
Ending Address: 0x000FFFFFFFF
Range Size: 2 GB
Partition Row Position: 1

Memory Device
Total Width: 64 bits
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: A1_DIMM3
Bank Locator: A1_BANK3
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: A1_Manufacturer3
Serial Number: A1_SerNum3
Asset Tag: A1_AssetTagNum3
Part Number: Array1_PartNumber3
Rank: Unknown
Configured Clock Speed: 66 MHz

32-bit Memory Error Information
Type: OK
Granularity: Unknown
Operation: Unknown
Vendor Syndrome: Unknown
Memory Array Address: Unknown
Device Address: Unknown
Resolution: Unknown

System Boot Information
Status: No errors detected

Management Device
Description: LM78-1
Type: LM78
Address: 0x00000000
Address Type: I/O Port

Voltage Probe
Description: LM78A
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Temperature Probe
Description: LM78A
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Cooling Device
Type: <OUT OF SPEC>
Status: <OUT OF SPEC>
Cooling Unit Group: 1
OEM-specific Information: 0x00000000
Nominal Speed: Unknown Or Non-rotating
Description: Cooling Dev 1

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Cooling Device
Type: <OUT OF SPEC>
Status: <OUT OF SPEC>
Cooling Unit Group: 1
OEM-specific Information: 0x00000000
Nominal Speed: Unknown Or Non-rotating
Description: Not Specified

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Electrical Current Probe
Description: ABC
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data

Management Device Component
Description: To Be Filled By O.E.M.

System Power Supply
Power Unit Group: 1
Location: To Be Filled By O.E.M.
Name: To Be Filled By O.E.M.
Manufacturer: To Be Filled By O.E.M.
Serial Number: To Be Filled By O.E.M.
Asset Tag: To Be Filled By O.E.M.
Model Part Number: To Be Filled By O.E.M.
Revision: To Be Filled By O.E.M.
Max Power Capacity: Unknown
Status: Not Present
Type: <OUT OF SPEC>
Input Voltage Range Switching: <OUT OF SPEC>
Plugged: Yes
Hot Replaceable: No

Management Device
Description: 2
Type: LM78
Address: 0x00000000
Address Type: I/O Port

Voltage Probe
Description: LM78B
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 7
Upper Non-critical Threshold: 8
Lower Critical Threshold: 8
Upper Critical Threshold: 10
Lower Non-recoverable Threshold: 11
Upper Non-recoverable Threshold: 12

Management Device Component
Description: To Be Filled By O.E.M.

Voltage Probe
Description: LM78B
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 13
Upper Non-critical Threshold: 14
Lower Critical Threshold: 15
Upper Critical Threshold: 16
Lower Non-recoverable Threshold: 17
Upper Non-recoverable Threshold: 18

Management Device Component
Description: To Be Filled By O.E.M.

Temperature Probe
Description: LM78B
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Cooling Device
Type: <OUT OF SPEC>
Status: <OUT OF SPEC>
Cooling Unit Group: 1
OEM-specific Information: 0x00000000
Nominal Speed: Unknown Or Non-rotating
Description: Cooling Dev 2

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Temperature Probe
Description: LM78B
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Cooling Device
Type: <OUT OF SPEC>
Status: <OUT OF SPEC>
Cooling Unit Group: 1
OEM-specific Information: 0x00000000
Nominal Speed: Unknown Or Non-rotating
Description: Cooling Dev 2

Management Device Threshold Data
Lower Non-critical Threshold: 1
Upper Non-critical Threshold: 2
Lower Critical Threshold: 3
Upper Critical Threshold: 4
Lower Non-recoverable Threshold: 5
Upper Non-recoverable Threshold: 6

Management Device Component
Description: To Be Filled By O.E.M.

Electrical Current Probe
Description: DEF
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data

Management Device Component
Description: To Be Filled By O.E.M.

Electrical Current Probe
Description: GHI
Location: <OUT OF SPEC>
Status: <OUT OF SPEC>
Maximum Value: Unknown
Minimum Value: Unknown
Resolution: Unknown
Tolerance: Unknown
Accuracy: Unknown
OEM-specific Information: 0x00000000
Nominal Value: Unknown

Management Device Threshold Data

Management Device Component
Description: To Be Filled By O.E.M.

System Power Supply
Power Unit Group: 1
Location: To Be Filled By O.E.M.
Name: To Be Filled By O.E.M.
Manufacturer: To Be Filled By O.E.M.
Serial Number: To Be Filled By O.E.M.
Asset Tag: To Be Filled By O.E.M.
Model Part Number: To Be Filled By O.E.M.
Revision: To Be Filled By O.E.M.
Max Power Capacity: Unknown
Status: Not Present
Type: <OUT OF SPEC>
Input Voltage Range Switching: <OUT OF SPEC>
Plugged: Yes
Hot Replaceable: No

Processor Information
Socket Designation: SOCKET 0
Type: Central Processor
Family: Core i5
Manufacturer: Intel
ID: A7 06 02 00 FF FB EB BF
Signature: Type 0, Family 6, Model 42, Stepping 7
Flags:
FPU (Floating-point unit on-chip)
VME (Virtual mode extension)
DE (Debugging extension)
PSE (Page size extension)
TSC (Time stamp counter)
MSR (Model specific registers)
PAE (Physical address extension)
MCE (Machine check exception)
CX8 (CMPXCHG8 instruction supported)
APIC (On-chip APIC hardware supported)
SEP (Fast system call)
MTRR (Memory type range registers)
PGE (Page global enable)
MCA (Machine check architecture)
CMOV (Conditional move instruction supported)
PAT (Page attribute table)
PSE-36 (36-bit page size extension)
CLFSH (CLFLUSH instruction supported)
DS (Debug store)
ACPI (ACPI supported)
MMX (MMX technology supported)
FXSR (FXSAVE and FXSTOR instructions supported)
SSE (Streaming SIMD extensions)
SSE2 (Streaming SIMD extensions 2)
SS (Self-snoop)
HTT (Multi-threading)
TM (Thermal monitor supported)
PBE (Pending break enabled)
Version: Intel(R) Core(TM) i5-2300 CPU @ 2.80GHz
Voltage: 0.0 V
External Clock: 100 MHz
Max Speed: 3800 MHz
Current Speed: 1600 MHz
Status: Populated, Enabled
Upgrade: Socket BGA1155
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
Core Count: 4
Core Enabled: 4
Thread Count: 4
Characteristics:
64-bit capable

BIOS Language Information
Language Description Format: Long
Installable Languages: 15
en|US|iso8859-1
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
<BAD INDEX>
Currently Installed Language: en|US|iso8859-1

[matt_symes]

Hi

What do your logs say around the time it crashes ?

Kind regards

[ahallubuntu]

What's the history of this box? Was it fine for a while then suddenly started this behavior? Or has it always been this way?

I'd try to remove as much as you can and still POST and run Memtest. So, unplug all drives, USB devices (except keyboard) and other add-in cards that you can and see if you can run Memtest successfully.

Does Memtest do the same thing (screen-wise)? Or does it just have other issues?

I couldn't get from your posted info whether this has a discrete video card or whether you are using integrated video - but if you have a separate card, you might try re-seating it. Or, if there's an option to remove it and use onboard video for testing, try that. But the issue may have nothing to do with video.

Some possibilities that come to mind:
- bad or incompatible RAM
- CPU overheating (fan not working or clogged with dust dirt; heat sink not seated properly)
- power supply failing or underpowered for the hardware
- motherboard failing (look for possible blown caps, though this appears not to be an ancient motherboard)

[tgalati4]

Strip everything out of the machine, minimum RAM, perhaps another graphics card and test it. Run memtest for 30 complete passes. Then try running Ubuntu for a few days in this minimum condition. Test your power supply with a voltmeter while it's running.

If it passes, then add components one at a time, running a few days to see any change in behavior. It could be a defective motherboard. They are assembled with toothpaste and hot glue these days.

[jonhall]

Thanks for the tips/pointers! The PC is about 1.5 years old. I don't remember noticing this problem right after it was built, but it has been happening for quite a while now. I checked the system log and there is nothing unusual around the time that it crashed. I also thought of CPU overheating and have kept an eye on temps, but I haven't noticed anything out of the ordinary.

Memtest does run successfully (usually); I just had the same screen issue once when running memtest, which led me to the conclusion that it's probably a hardware issue rather than a software/OS problem. The system is fairly bare-bones; there isn't a lot connected to it, no expansion cards, and it's using integrated video.

I haven't tested the PSU; perhaps I should look there. Otherwise I would think it's probably the motherboard, but I'm not sure how to know for sure. It may still be under warranty, but since this is a fairly random problem I'm not sure how to prove that it's defective.

[tgalati4]

Put your finger on the integrated graphics chip/heatsink. If you can't keep your finger on it (because it is too hot), then that might be your problem. Add a small fan to the heatsink, or put in another video card so that the integrated video is turned off.

[jonhall]

Hmmm... right now it's warm, but not hot. I'll have to try that when it crashes next to see what it feels like then. Thanks for the suggestion!

[ahallubuntu]

Memtest does run successfully (usually);

What do you mean "usually?" Have you tried other RAM besides what's in there now? It should ALWAYS run successfully unless you have some other reason for it.

You could have bad RAM or RAM that's not compatible with that motherboard.

[jonhall]

What I meant is that memtest doesn't fail or report any memory errors. However, the computer has crashed while running memtest, in the same way that it has when running Ubuntu.

[tgalati4]

It is common for graphics chips and IO-bridge chips to delaminate from the motherboard. They are soldered to the motherboard with ~700 balls of tiny solder, known as ball grid array (BGA). With lead-free solder of newer boards, these joints fail on chips that get hot. Pressure on the chip can make contact and improve uptime, but repair is difficult with high failure rate. Of course it could be a corroded copper trace on the motherboard. The fact that the machine locks up during memtest is a good indicator that the motherboard is suspect. But you can't rule out the power supply either. All it takes is one capacitor to start shorting when hot and you have power dropouts.

[Linuxisfast]

Most likely its your vga cable or video card going bad, mine did the same before it packed off.