No error message given and system still works. Same result on Ubuntu, Chrunchbang and Fedora 12. Maximum speed 533 but size is recognised. Tried on another machine all is well.
Errant hardware is ASRock N68-S with AMD AthlonX2 5050e. Stated as compatible on the asrock ref.
read out with corsair 2gb 677:
[d.duck@localhost ~]$ su
Password:

localhost.localdomain
description: Desktop Computer
product: To Be Filled By O.E.M.
vendor: To Be Filled By O.E.M.
version: To Be Filled By O.E.M.
serial: To Be Filled By O.E.M.
width: 32 bits
capabilities: smbios-2.4 dmi-2.4 smp-1.4 smp
configuration: boot=normal chassis=desktop cpus=2 uuid=00020003-0004-0005-0006-000700080009
*-core
description: Motherboard
product: N68-S
vendor: ASRock
physical id: 0
*-firmware
description: BIOS
vendor: American Megatrends Inc.
physical id: 0
version: P1.50 (07/17/2009)
size: 64KiB
capacity: 448KiB
capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification netboot
*-cpu:0
description: CPU
product: AMD Athlon(tm) Dual Core Processor 5050e
vendor: Advanced Micro Devices [AMD]
physical id: 3
bus info: cpu@0
version: 15.11.2
serial: To Be Filled By O.E.M.
slot: CPUSocket
size: 2600MHz
capacity: 2600MHz
width: 64 bits
clock: 200MHz
capabilities: boot fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp x86-64 3dnowext 3dnow extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch cpufreq
*-cache:0
description: L1 cache
physical id: 5
slot: L1-Cache
size: 256KiB
capacity: 256KiB
capabilities: pipeline-burst internal varies data
*-cache:1
description: L2 cache
physical id: 6
slot: L2-Cache
size: 1MiB
capacity: 1MiB
capabilities: pipeline-burst internal varies unified
*-memory:0
description: System Memory
physical id: e
slot: System board or motherboard
size: 2GiB
*-bank:0
description: DIMM DDR2 Synchronous 533 MHz (1.9 ns)
product: PartNum0
vendor: Manufacturer0
physical id: 0
serial: SerNum0
slot: DIMM0
size: 2GiB
width: 64 bits
clock: 533MHz (1.9ns)
*-bank:1
description: DIMM [empty]
product: PartNum1
vendor: Manufacturer1
physical id: 1
serial: SerNum1
slot: DIMM1
*-cpu:1
physical id: 4
bus info: cpu@1
version: 15.11.2
size: 2600MHz
capacity: 2600MHz
capabilities: cpufreq
*-memory:1 UNCLAIMED
description: RAM memory
product: MCP61 LPC Bridge
vendor: nVidia Corporation
physical id: a
bus info: pci@0000:00:00.0
version: a1
width: 32 bits
clock: 66MHz (15.2ns)
capabilities: ht bus_master cap_list
configuration: latency=0
*-isa
description: ISA bridge
product: MCP61 LPC Bridge
vendor: nVidia Corporation
physical id: 1
bus info: pci@0000:00:01.0
version: a2
width: 32 bits
clock: 66MHz
capabilities: isa bus_master
configuration: latency=0
resources: ioport:900(size=256)
*-serial
description: SMBus
product: MCP61 SMBus
vendor: nVidia Corporation
physical id: 1.1
bus info: pci@0000:00:01.1
version: a2
width: 32 bits
clock: 66MHz
capabilities: pm cap_list
configuration: driver=nForce2_smbus latency=0
resources: irq:11 ioport:dc00(size=64) ioport:600(size=64) ioport:700(size=64)
*-memory:2 UNCLAIMED
description: RAM memory
product: MCP61 Memory Controller
vendor: nVidia Corporation
physical id: 1.2
bus info: pci@0000:00:01.2
version: a2
width: 32 bits
clock: 66MHz (15.2ns)
configuration: latency=0
*-usb:0
description: USB Controller
product: MCP61 USB Controller
vendor: nVidia Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: a3
width: 32 bits
clock: 66MHz
capabilities: pm ohci bus_master cap_list
configuration: driver=ohci_hcd latency=0 maxlatency=1 mingnt=3
resources: irq:22 memory:fbeff000-fbefffff
*-usbhost
product: OHCI Host Controller
vendor: Linux 2.6.32.9-70.fc12.i686.PAE ohci_hcd
physical id: 1
bus info: usb@2
logical name: usb2
version: 2.06
capabilities: usb-1.10
configuration: driver=hub slots=9 speed=12.0MB/s
*-usb:1
description: USB Controller
product: MCP61 USB Controller
vendor: nVidia Corporation
physical id: 2.1
bus info: pci@0000:00:02.1
version: a3
width: 32 bits
clock: 66MHz
capabilities: debug pm ehci bus_master cap_list
configuration: driver=ehci_hcd latency=0 maxlatency=1 mingnt=3
resources: irq:23 memory:fbefec00-fbefecff
*-usbhost
product: EHCI Host Controller
vendor: Linux 2.6.32.9-70.fc12.i686.PAE ehci_hcd
physical id: 1
bus info: usb@1
logical name: usb1
version: 2.06
capabilities: usb-2.00
configuration: driver=hub slots=9 speed=480.0MB/s
*-pci:0
description: PCI bridge
product: MCP61 PCI bridge
vendor: nVidia Corporation
physical id: 100
bus info: pci@0000:00:04.0
version: a1
width: 32 bits
clock: 66MHz
capabilities: pci ht subtractive_decode bus_master cap_list
resources: ioport:e000(size=4096) memory:fbf00000-fbffffff memory:70000000-700fffff(prefetchable)
*-storage
description: Mass storage controller
product: IT/ITE8212 Dual channel ATA RAID controller
vendor: Integrated Technology Express, Inc.
physical id: a
bus info: pci@0000:01:0a.0
logical name: scsi1
version: 13
width: 32 bits
clock: 66MHz
capabilities: storage pm bus_master cap_list rom emulated
configuration: driver=pata_it821x latency=64 maxlatency=8 mingnt=8
resources: irq:19 ioport:ec00(size=8) ioport:e880(size=4) ioport:e800(size=8) ioport:e480(size=4) ioport:e400(size=16) memory:70000000-7001ffff(prefetchable)
*-disk
description: ATA Disk
product: Maxtor 2F040L0
vendor: Maxtor
physical id: 0.0.0
bus info: scsi@1:0.0.0
logical name: /dev/sda
version: VAM5
serial: F1KCT4AE
size: 38GiB (41GB)
capabilities: partitioned partitioned:dos
configuration: ansiversion=5 signature=96559655
*-volume:0
description: EXT4 volume
vendor: Linux
physical id: 1
bus info: scsi@1:0.0.0,1
logical name: /dev/sda1
logical name: /boot
version: 1.0
serial: 305d3ccf-e512-4d0e-98de-8ebe60c4952b
size: 200MiB
capacity: 200MiB
capabilities: primary bootable journaled extended_attributes huge_files dir_nlink extents ext4 ext2 initialized
configuration: created=2010-01-20 10:46:03 filesystem=ext4 lastmountpoint=/boott%箹����������������vL���S���S����B�О��wL����t� modified=2010-03-11 20:50:19 mount.fstype=ext4 mount.options=rw,seclabel,relatime,barrier=1,data=ordered mounted=2010-03-11 20:36:48 state=mounted
*-volume:1
description: Linux LVM Physical Volume partition
physical id: 2
bus info: scsi@1:0.0.0,2
logical name: /dev/sda2
serial: na10wf-xxrr-aV37-VKVR-dSTt-TKR9-qMunSe
size: 38GiB
capacity: 38GiB
capabilities: primary multi lvm2
*-multimedia
description: Audio device
product: MCP61 High Definition Audio
vendor: nVidia Corporation
physical id: 5
bus info: pci@0000:00:05.0
version: a2
width: 32 bits
clock: 66MHz
capabilities: pm msi ht bus_master cap_list
configuration: driver=HDA Intel latency=0 maxlatency=5 mingnt=2
resources: irq:21 memory:fbef8000-fbefbfff
*-ide:0
description: IDE interface
product: MCP61 IDE
vendor: nVidia Corporation
physical id: 6
bus info: pci@0000:00:06.0
logical name: scsi0
version: a2
width: 32 bits
clock: 66MHz
capabilities: ide pm bus_master cap_list emulated
configuration: driver=pata_amd latency=0 maxlatency=1 mingnt=3
resources: irq:0 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:ffa0(size=16)
*-cdrom
description: DVD-RAM writer
product: DVD RW AW-G170A
vendor: SONY
physical id: 0.1.0
bus info: scsi@0:0.1.0
logical name: /dev/cdrom
logical name: /dev/cdrw
logical name: /dev/dvd
logical name: /dev/dvdrw
logical name: /dev/scd0
logical name: /dev/sr0
version: 1.71
serial: [SONY DVD RW AW-G170A 1.71 Jul19,2006
capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
configuration: ansiversion=5 status=nodisc
*-bridge
description: Ethernet interface
product: MCP61 Ethernet
vendor: nVidia Corporation
physical id: 7
bus info: pci@0000:00:07.0
logical name: eth0
version: a2
serial: 00:19:66:f5:e0:fd
size: 100000000
capacity: 100000000
width: 32 bits
clock: 66MHz
capabilities: bridge pm msi ht bus_master cap_list ethernet physical mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=forcedeth driverversion=0.64 duplex=full ip=192.168.0.100 latency=0 link=yes maxlatency=20 mingnt=1 multicast=yes port=MII speed=100MB/s
resources: irq:27 memory:fbefd000-fbefdfff ioport:d480(size=8)
*-ide:1
description: IDE interface
product: MCP61 SATA Controller
vendor: nVidia Corporation
physical id: 8
bus info: pci@0000:00:08.0
version: a2
width: 32 bits
clock: 66MHz
capabilities: ide pm msi ht bus_master cap_list
configuration: driver=sata_nv latency=0 maxlatency=1 mingnt=3
resources: irq:20 ioport:d400(size=8) ioport:d080(size=4) ioport:d000(size=8) ioport:cc00(size=4) ioport:c880(size=16) memory:fbefc000-fbefcfff
*-ide:2
description: IDE interface
product: MCP61 SATA Controller
vendor: nVidia Corporation
physical id: 8.1
bus info: pci@0000:00:08.1
version: a2
width: 32 bits
clock: 66MHz
capabilities: ide pm msi ht bus_master cap_list
configuration: driver=sata_nv latency=0 maxlatency=1 mingnt=3
resources: irq:23 ioport:c800(size=8) ioport:c480(size=4) ioport:c400(size=8) ioport:c080(size=4) ioport:c000(size=16) memory:fbef7000-fbef7fff
*-pci:1
description: PCI bridge
product: MCP61 PCI Express bridge
vendor: nVidia Corporation
physical id: 9
bus info: pci@0000:00:09.0
version: a2
width: 32 bits
clock: 33MHz
capabilities: pci pm msi ht pciexpress normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:24
*-pci:2
description: PCI bridge
product: MCP61 PCI Express bridge
vendor: nVidia Corporation
physical id: b
bus info: pci@0000:00:0b.0
version: a2
width: 32 bits
clock: 33MHz
capabilities: pci pm msi ht pciexpress normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:25
*-pci:3
description: PCI bridge
product: MCP61 PCI Express bridge
vendor: nVidia Corporation
physical id: c
bus info: pci@0000:00:0c.0
version: a2
width: 32 bits
clock: 33MHz
capabilities: pci pm msi ht pciexpress normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:26
*-display
description: VGA compatible controller
product: nVidia Corporation
vendor: nVidia Corporation
physical id: d
bus info: pci@0000:00:0d.0
version: a2
width: 64 bits
clock: 66MHz
capabilities: pm msi vga_controller bus_master cap_list rom
configuration: driver=nouveau latency=0
resources: irq:21 memory:fa000000-faffffff memory:e0000000-efffffff(prefetchable) memory:f9000000-f9ffffff memory:fbec0000-fbedffff(prefetchable)
*-pci:4
description: Host bridge
product: K8 [Athlon64/Opteron] HyperTransport Technology Configuration
vendor: Advanced Micro Devices [AMD]
physical id: 101
bus info: pci@0000:00:18.0
version: 00
width: 32 bits
clock: 33MHz
*-pci:5
description: Host bridge
product: K8 [Athlon64/Opteron] Address Map
vendor: Advanced Micro Devices [AMD]
physical id: 102
bus info: pci@0000:00:18.1
version: 00
width: 32 bits
clock: 33MHz
*-pci:6
description: Host bridge
product: K8 [Athlon64/Opteron] DRAM Controller
vendor: Advanced Micro Devices [AMD]
physical id: 103
bus info: pci@0000:00:18.2
version: 00
width: 32 bits
clock: 33MHz
*-pci:7
description: Host bridge
product: K8 [Athlon64/Opteron] Miscellaneous Control
vendor: Advanced Micro Devices [AMD]
physical id: 104
bus info: pci@0000:00:18.3
version: 00
width: 32 bits
clock: 33MHz
configuration: driver=k8temp
resources: irq:0

Any thoughts?

Fred.

Is the ram speed set in the bios ?

Thanks. I tried the bios option and I see what you mean but it would not let me into that field. Any further suggestions?

Fred.

Maybe there's another setting to change before it will let you in.

Is it set to auto ?

Have to find the manual ...
http://www.asrock.com/MB/manual.asp?Model=N68-S

Either that or the ram really is 533

Thanks.Yes I set most things to auto and it has never been a problem in the past. I have the manual already but not the raid variety which is a bonus. The sticks tried were 667 and 800. At the risk of sounding stupid what do I reset and what to?

Fred.