Processor machine check panic (Code = 98)

Hi managers,

Recently one of our PWS 500au running Tru64 Unix 4.0D PK3
panic'ed with a "Processor Machine Check" and
"Machine Check Code = 98".

Does anybody know how to find the faulty part?

Thanks in advance,

Christian.

=========== crash-data ============
[...]
_preserved_message_buffer_begin:
struct {
    hdr = struct {
        msg_magic = 0x880524
        msg_bufx = 0xf4
        msg_bufr = 0x7a4
        msg_size = 0xfe0
    }
    msg_bufc = " 0): Processor Machine Check
syncing disks... device string for dump = SCSI 0 1004 0 0 0 0 0.
DUMP.prom: dev SCSI 0 1004 0 0 0 0 0, block 524288
device string for dump = SCSI 0 1004 0 0 0 0 0.
DUMP.prom: dev SCSI 0 1004 0 0 0 0 0, block 524288

Digital Personal WorkStation 500au
Firmware revision: 7.1-3
PALcode: Digital UNIX version 1.22-0
pci0 at nexus
tu0: DECchip 21143: Revision: 3.0
tu0: auto negotiation capable device
tu0 at pci0 slot 3
tu0: DEC TULIP (10/100) Ethernet Interface, hardware address:
08-00-2B-86-88-11
tu0: auto negotiation off: selecting 10BaseT (UTP) port: half duplex
isa0 at pci0
gpc0 at isa0
ace0 at isa0
ace1 at isa0
lp0 at isa0
fdi0 at isa0
fd0 at fdi0 unit 0
ata0 at pci0 slot 107
ata0: Cypress 82C693
scsi0 at ata0 slot 0
ata1 at pci0 slot 207
ata1: Cypress 82C693
scsi1 at ata1 slot 0
rz8 at scsi1 target 0 lun 0 (LID=0) (COMPAQ  CRD-8322B        1.07)
ohci0 at pci0 slot 307 (slot 7, function 3)
tu1: DECchip 21041: Revision: 2.1
tu1 at pci0 slot 11
tu1: DEC TULIP (10Mbps) Ethernet Interface, hardware address:
08-00-2B-C4-71-C7
tu1: console mode: selecting 10Base5 (AUI) port
tu2: DECchip 21041: Revision: 2.1
tu2 at pci0 slot 12
tu2: DEC TULIP (10Mbps) Ethernet Interface, hardware address:
08-00-2B-C4-70-3D
tu2: console mode: selecting 10BaseT (UTP) port: half duplex
pci1000 at pci0 slot 20
isp0 at pci1000 slot 4
isp0: QLOGIC ISP1040B/V2
isp0: Firmware revision 5.57 (loaded by console)
scsi2 at isp0 slot 0
rz16 at scsi2 target 0 lun 0 (LID=1) (COMPAQ  BB00921B91       3B05)
(Wide16)
isp1 at pci1000 slot 8
isp1: QLOGIC ISP1040B/V2
isp1: Firmware revision 5.57 (loaded by console)
isp1: Fast RAM timing enabled.
scsi3 at isp1 slot 0
lvm0: configured.
lvm1: configured.
kernel console: ace0
dli: configured
ATM Subsystem configured with 1 restart threads
ATM IFMP: configured
ATM UNI 3.x signalling: configured
ATM IP interface: configured
LAN Emulation: configured
Environmental Monitoring Subsystem Configured.
Machine Check Processor Fatal Abort
Machine Check Code = 98
Processor detected hard error
	pal temp[0-1]		= ffffffff88084000 0000000000000c70
	pal temp[2-3]		= fffffc000052e2d0 0000000000005200
	pal temp[4-5]		= 0000000000002000 ffffffff88087838
	pal temp[6-7]		= 0000000000000000 fffffc000052dbf0
	pal temp[8-9]		= 1f1e161514020100 fffffc000052e010
	pal temp[10-11]		= fffffc000052d118 fffffc000052de70
	pal temp[12-13]		= fffffc000052e240 fffffffffff85200
	pal temp[14-15]		= 0000000000f00270 0000000000f0380c
	pal temp[16-17]		= 0000009806700001 0000000000000000
	pal temp[18-19]		= 000000011ffff950 ffffffff88087a38
	pal temp[20-21]		= 0000000000234000 fffffc000052e270
	pal temp[22-23]		= fffffc00006e3200 0000000003709a38
	shadow[0-1]		= 0000000000000000 0000000000000000
	shadow[2-3]		= 0000000000000000 0000000000000000
	shadow[4-5]		= 0000000000000000 0000000000000000
	shadow[6-7]		= 0000000000000000 0000000000000000
	Address of excepting instruction	= fffffc000052d118
	Summary of arithmetic traps	= 0000000000000000
	Exception mask			= 0000000000000000
	Base address for PALcode	= 0000000000018000
	Interrupt Status Reg		= 0000000000000000
	CURRENT SETUP OF EV5 IBOX	= 0000004162020000
	I-CACHE Reg Tag parity error	= 0000000000000000
	D-CACHE error Reg		= 0000000000000000
	Effective VA		= ffffffff80280a08
	reason for D-stream	= 0000000000014990
	EV5 Secondary Cache address	= ffffff000001d08f
	EV5 Secondary Cache TAG/Data parity	= 0000000000000000
	EV5 BC_TAG_ADDR		= ffffff8000cf7fff
	EV5 EI_STAT_ADDR Phys addr of Xfer	= ffffff0000f9dfdf
	Fill Syndrome		= 000000000000d200
	EI_STAT reg		= fffffff105ffffff
	LD_LOCK			= ffffff00001e66ff
	PYXIS_DMA_DATA		= 0000000000000000
	CIA/PYXIS ERR			= 0000000000000000
	CIA/PYXIS ERR STAT		= 0000000000000000
	CIA/PYXIS ERR MASK		= 0000000000000b93
	CIA/PYXIS ECC_SYN		= 0000000000000000
	CIA/PYXIS MEM ERR0		= 000000000581d580
	CIA/PYXIS MEM ERR1		= 0000000058000000
	CIA/PYXIS PCI ERR0		= 0000000007010206
	CIA/PYXIS PCI ERR1		= ffffffff801d1108
	ISA bridge NMI status & control	= 0000000000000000
	CIA/PYXIS PCI ERR2		= 0000000047fe4880
panic (cpu"
}
_preserved_message_buffer_end:
[...]
=========== crash-data ============

-- 
Christian