[Info-vax] RAM errors?

[MG]

Dear regulars,

Recently I had a very unfortunate problem with one of my rx2600s, which 
I had powered off for several days.  Yesterday I powered it up again and 
rebooted it more than once.  At some point, the system hung (after
successfully booted into OpenVMS) and I believe I had to do a power 
cycle (via iLO).  Later the EFI presented me with a series of memory 
(RAM) errors, as seen below:
_________________________________________________________________________

3 0 0x000FA0 0xFFFFFFFF000AFF74 DRAM failure on DIMM 0A, deallocate rank
3 0 0x000FA0 0xFFFFFFFF000AFF74 DRAM failure on DIMM 0A, deallocate rank
3 0 0x000FA0 0xFFFFFFFF004AFF74 DRAM failure on DIMM 4A, deallocate rank
3 0 0x000FA0 0xFFFFFFFF002AFF74 DRAM failure on DIMM 2A, deallocate rank
_________________________________________________________________________


After reseating the DIMMs on the above mentioned locations, the system 
'works' again (up to this very moment of writing this message) and the 
errors have seemingly disappeared.

The reason I rebooted was because sometimes there would be visual 
artifacts in the screen (in weird varying 'quantities').  Strangely 
enough, these visual artifacts appear to be caused whenever I'd have a 
simultaneous serial console connection or after I rebooted from a 
console.  However, now it almost seems as if the visual artifacts are 
showing up more frequently than before.

The video card in question is a Radeon 7500 (PCI), I have two of them 
and both are installed in rx2600s (they should be identical, I purchased 
them from one and the same retailer).  Another thing that I've noticed 
is that the Radeon 7500 in the other rx2600 provides EFI graphics 
output, while the other one --- the system with the [memory] issues --- 
does not.  Both rx2600s have the same firmware and I'm not aware of any 
specific Radeon 7500 firmware.

Could all of this be caused by faulty memory, or is perhaps the PCI card 
backplane faulty?  Maybe even the system board?  Because, although the 
system is up and running again, I'm not very confident about it and I 
wonder for how long that will be...

  - MG