In article , GlassVial
wrote:

My A7V v1.02 is having an odd problem, I can use 1 stick of memory
without an issue, but when I add a second (or third), memtest throws
errors like crazy. I've read 30+ pages back in this forum, tried
searching it, and have still not found the answer yet. I've tried all
3 VIO jumper settings (no difference) and I have 6 sticks of PC133
memory at my disposal to try. 2 Kingston, 2 PNY, 1 infineon and 1
micron. I flashed the BIOS to 1012beta just to see if it would help
(it didn't). All 6 sticks are known good, they all test perfect in
another system (together and individually). I tried memtest 3.1a and
memtest+ v1.26 (doesn't matter, they both throw the errors). Tried
setting it to PC100 or PC133, doesn't make a difference. Manually set
the timings to 3T/3T/3T also. CPU is a Duron 1300.

I'm at the end of my rope here, I'm about ready to throw this board
out the window and swear off Asus for good unless someone has some
suggestions for me

-GV

You should be using groups.google.com to research the issue. I tried
A7V and "three sticks" as two search terms (incl. the double quotes
so that the two words three and sticks are found together).

http://groups.google.com/groups?thre...6.2 21.81.119

You could also try private forums specializing in your board, like
a7vtroubleshooting.com .

Experience with RAM will vary from board to board, and with different
brands of memory DIMMs. The basic problem is, a shared memory bus has
poor signal integrity, so the speed versus number of sticks problem
will _always_ be an issue. (The upcoming Intel FB memory stick will
solve this problem once and for all, as Intel has some kind of
hub architecture for memory in the works.)

First of all, try to get two sticks running, using slot1 and slot3.
Leave slot2 blank for now. You may be able to run at full speed that
way.

To run three sticks, might require using single sided RAM (which of
course does nothing good for you in terms of total RAM on board - two
double sided sticks will give more total RAM). Using a double sided
in the slot furthest from the processor, and two single sided nearest
the processor, is another potential config, again doing nothing for
you in terms of max memory.

I have read accounts of this problem with later board models, and
occasionally someone will manage to get a board full of RAM running
at full speed, but it doesn't happen that often.

There are a couple of solutions to the problem.

One is boards that use registered memory. This is typically server
boards, but there are some desktop boards that can use registered
as well. Registered memory has a latch on the address bus, and its
main benefit, is the fact that the latch drives the address to the
memory chips, removing the heavy capacitive load from the address
bus. This allows the Northbridge to drive more memory loads without
a problem. The single electrical load of the latch chip causes much
less transmission line discontinuity than does 16 memory chips in
parallel sitting on the address bus.

A second solution, is for a motherboard to have multiple address
busses with the same info on them. The Athlon64 S754 processor does
this, and there have been a number of chipsets in the past that
have done this as well (Nforce2 is an example).

So, I wouldn't single out Asus as the only maker suffering from the
problem. If you know a bit more about the electrical nature of the
problem and its solutions, that can make finding a board that can
take a full load of DIMMs a bit easier.

For example, dual channel boards with four sockets, have two
DIMMs on one bus and two DIMMs on the other bus. That is one way
of buying a product with two address busses. However, you still
have to check Google, and read the manual for a given board,
before buying, because some chip designers still don't get it.
For example, the ATI chipsets don't seem to be up to the job,
based on some comments I've read yesterday in a Corsair forum.

HTH,
Paul