tg said:
what is the correct software to use to test DDR3 memory on a 64 bit
PC? I have 4 sticks of 2Gb ram DDR3 1333 samsung. A couple of the
sticks are glitchy (returning to supplier) and I wish to test the
remaining two, which are plugged in to an asus M4A785T-M motherboard
running a AMD Phenom II 965 cpu. I have memtest86 v4.00 but I don't
know if this is the right software for the job Thanks for any advice.
That software should be fine. I don't have any "big RAM" machines to test
it on, but they claim they support it in their official forum.
http://forum.canardpc.com/showthread.php?t=28878&page=2
"(Post #37)
Memtest is able to test up to 64GB, but it needs PAE support to do so."
AMD documents 32559.pdf and 41256.pdf are "BIOS Writer's Guides" that
contain additional information about AMD products (that is, if you can
decode what processor they're talking about). This is an example
from one of the documents.
"Sizing and Testing Memory above 4 Gbytes
AMD NPT Family 0Fh Processors have extended physical address extension
(PAE) to support a 40-bit address space. Thus, the BIOS can set up a
32-bit page table that allows it to size and test all physical memory
in the system."
What that means is, if so equipped (i.e. supports PAE), a memory test
program can set up a mapping, and test a mapped "chunk" of memory, from
the entire address space. Even though the code may be limited to
computing a 32 bit address, that would be effectively added to
whatever base address was achieved by mapping. So you don't actually
need a 64 bit executable, to test memory above 4GB.
On the original PAE implementation from Intel, the number of bus bits
between the processor and the Northbridge was 36 bits. 32 bits would be
4GB. 36 bits is four more bits and four bits gives an extra factor of 16.
16*4GB = 64GB, which is what Post #37 above is referring to. The AMD
statement indicates for that particular processor, they support 40 bits,
and you can't stuff enough DIMMs into a desktop system, to hit that limit.
On an AMD desktop, PAE should be able to cover whatever you install
(up to whatever the per-slot addressing limit happens to be, which
is pretty hard to figure out). 8GB should be no problem at all.
A 32 bit OS can also actually support operation with more than 4GB
of memory. But Microsoft chooses to limit what you can do. There are
some tests carried out here, where a modification to a Microsoft OS,
allowed a 32 bit version to address more than 4GB.
http://www.geoffchappell.com/viewer.htm?doc=notes/windows/license/memory.htm
Paul
