Problems with AMD64 and 8 GB RAM? (solved)

Danny Pansters danny at
Mon Apr 4 18:17:37 PDT 2005

<snipped everything hehehe how evil>

This may not be related at all, but I've been following this thread and at 
certain times I wanted to drop in and stress that things like pci express 
cards should be re-inserted after the RAM has been (re)inserted. Perhaps the 
BIOSes are really that stupid that they only rely on memory adresses assigned 
by when you plugged in what. Anyway, it may not matter at all for you but 
knowing the kind of inquiring mind you have, and considering that this was 
one of the "sorta-would-it-matter" things hanging over this discussion, 
perhaps it's a point of interest also. This is how I understand it:

FreeBSD 5.4-PRERELEASE #0: Fri Apr  1 01:16:43 CEST 2005
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Pentium(R) 4 CPU 3.40GHz (3400.12-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf34  Stepping = 4
  Hyperthreading: 2 logical CPUs
real memory  = 1071837184 (1022 MB)
avail memory = 1035120640 (987 MB)
mptable_probe: MP Config Table has bad signature: \M^?\M^?\M^?\M^?
ACPI APIC Table: <INTEL  D925CV2 >

[part of dmesg with this board]

I have a rather new uniprocessor Intel board and the manual specifically 
stressed (in the light of the 4 BG limit and the &*^*&^:-o things BIOSes 
might do to overcome that -- the bios will want to have that reserved adress 
pool just below the 4 GB and depending on the bios it can map it above 4GB 
perhaps) that any pci express cards (my graphics card) must be inserted AFTER 
the RAM. Also, about the pairing of DDR2 RAM: you must alight the ram in both 
channels in principle (that is both in A not B), but if you don't it works if 
you have the same totals. Again, mobo docs should have all the quirky rules.

I didn't want to disturb the discussion but in retrospective, I feel that 
perhaps some of these points might matter. My observations are on i386 not 
amd64 but the same kind of logic seems to apply AFAICT.

HTH, (in retrospective of course ;-)


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