Power PC G5 - scren goes grey and following message appears

Question

This has happened 8 times today. Anything I can do. I receive the following message, and am told to power down holding the power button.
panic(cpu 0 caller 0x00C1917C): DART XBE DART Entry Exception: HyperTransport write logical page 0x00000
Latest stack backtrace for cpu 0:
Backtrace:
0x000954F8 0x00095A10 0x00026898 0x00C1917C 0x00B60D70 0x00B60DA8 0x00747048 0x002D1B8C
0x002D0A54 0x000A9714
Kernel loadable modules in backtrace (with dependencies):
com.apple.driver.AppleGPIO(1.1.9d0)@0xb5e000
dependency: com.apple.driver.IOPlatformFunction(1.8.0d12)@0x6c0000
com.apple.driver.MacIOGPIO(1.1.9d0)@0x745000
com.apple.driver.AppleMacRISC4PE(1.8.6f1)@0xc12000
dependency: com.apple.iokit.IOPCIFamily(1.7)@0x4ea000
dependency: com.apple.driver.IOPlatformFunction(1.8.0d12)@0x6c0000
Proceeding back via exception chain:
Exception state (sv=0x00ECA780)
PC=0x00000000; MSR=0x0000D030; DAR=0x00000000; DSISR=0x00000000; LR=0x00000000; R1=0x00000000; XCP=0x00000000 (Unknown)
Kernel version:
Darwin Kernel Version 8.11.0: Wed Oct 10 18:26:00 PDT 2007; root:xnu-792.24.17~1/RELEASE_PPC

Answer 1

Hi Carll14, and a warm welcome to the forums!
Resolving Kernel Panics...
http://www.thexlab.com/faqs/kernelpanics.html
See
Dr. Smoke's post here...
"This type of panic generally indicates a that a device has attempted to perform a Direct Memory Access (DMA) read or write to an unprepared page. DMA involves accessing memory while bypassing the CPU, a function of all modern computer architectures. Hypertransport is a high-speed bus architecture between the computer's memory controller and its device I/O.
Specifically, a device has tried to read or write memory via DMA that has not been prepared by an IOMemoryDescriptor.
Read-related panics reveal themselves by beginning in the panic log:
Code:
panic(cpu 1 caller hexaddress1): DART entry exception: HyperTransport read logical page hexaddress2
Write-related panic begins
Code:
panic(cpu 1 caller hexaddress1): DART entry exception: HyperTransport write logical page hexaddress2
where hexaddressn is a hexadecimal addresses, such as 0x00D4FAEC or 0x00C40.
The first Power Mac G5 desktops did not have an error facility for the DMA Address Relocation Table (DART). All later Power Mac G5 computers have such a facility. A kernel panic results when a PCI bus master device accesses memory at an address that is not mapped by the DART. Examples of PCI bus master devices include disk controllers, RAID controllers, and video cards employing DMA.
Generally this indicates an incompatible peripheral, often a PCI card, but incompatible AGP cards can also cause problems."