"John" said:
I just downloaded the manual from the asus site. I have 3 dimms of ddr 400
ram. 1 is 512megs and the other 2 are a matched pair of 256megs each. If I
am reading this chart right in the manual, I can't run 3 sticks of ddr 400
ram on this motherboard. Is that right? Oh yea, it is OCZ PC 3200
performance series. It had a copper spread on it and it did not pay
attention if it was single or double sided.
Thanks in advance
It looks like D-S-S is DDR333 max and D-x-D is DDR400. So, the chart
seems to be saying no. Try it anyway, it just might work. The purpose
of the chart, is to show you how sensitive the electrical performance
is to bus loading and chosen clock speed. There may be enough device
to device variation, that your three sticks might work - but no
guarantee. If it doesn't work, you'll need to dial the memory clock
down to DDR333.
This block diagram shows that the processor drives the memory directly.
Ignore the two busses shown.
http://www.via.com.tw/en/k8-series/k8t800.jsp
Based on the block diagram, I downloaded the datasheet for the processor
from AMD:
Athlon 64 (754 pin, single memory bus)
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/24659.PDF
There is some interesting reading in the AMD processor spec.
1) The memory chart Asus put in the manual, is copied out of the AMD
processor datasheet.
2) DIMM1 has its own address bus. DIMM2 and DIMM3 share an address bus.
That is why there is a detailed memory table in the AMD datasheet,
to show that the DIMM slots are not created equal. For example, if
you had a DIMM with heavy address loading, it should go in the first
slot and its private address bus. (The address busses are not logically
separated - they have identical information, and the "unused" address
on any given memory transaction is the 1's complement of the other
bus - this is to reduce switching noise inside the processor.)
3) There is a table in the AMD spec, that shows the real frequencies used
to drive the DIMMs. (Pg.14)
I think there is still a possibility of running three sticks, especially
if the 256MB are single sided. This is assuming, of course, that the BIOS
doesn't prevent you from running it the way you want - Asus BIOS have been
known to examine the memory config and crank the clock down when they see
too many DIMMs.
Get a copy of MEMTEST86 from memtest86.com and test the memory, before
installing an OS. Support for testing the ECC portion of a DIMM is dependent
on per-chipset support in MEMTEST86, so if the memory you own has ECC, the
ECC portion may not get tested. (See the docs on the memtest86 website.)
HTH,
Paul
