"shane" said:
I just bought 2 A7V880 motherboards and planned on one of them having 2GB of
ram for my home recording studio. Problem is, I can't get my PC to boot w/
2GB of ram. I updated to the latest BIOS and it still won't work. It will
boot up w/ 3 DIMMS (1.5GB) but not all 4. The PC just keeps rebooting at
post. I even took the memory out and placed it in the second A7V880 and same
thing happened to that board. I tried to slow down the memory timings and
all that did was make the motherboard only see 1GB instead of 2GB of ram...
is this a problem w/ the motherboard its self or is this a BIOS issue??
Thanks!!!!
You are doing what I would try. Slowing down the timings / memory
frequency. Try to keep the processor FSB and memory bus at the
same speed, for synchronous operation, as that is the best
setting for the hardware. (I don't understand how only 1GB is
detected, if the speed is reduced. Memory size info should come
from the SPD chip on the DIMM - the days of detecting memory size
by writing to the memory map and then doing a test read back, to
discover whether memory is really there, are long over.)
If the DIMMs had improperly programmed Serial Presence Detect (SPD)
EEPROMS (a tiny chip on the DIMM that records all the characteristics
of the memory), then that could upset the BIOS. it is hard to dump
the contents of that chip, as the chip sits on the SMBUS, and
Windows utilities have to be programmed for virtually every motherboard
individually. Sandra has a separate module, that may or may not have
been updated for the latest motherboards. I think Everest gives some
info, but virtually no utility just dumps the raw data bytes - that is
handy, to see how many of the bytes have been intelligently programmed
or not. Many cheap memories have minimal programming in the SPD -
just the memory speed is recorded, and many other fields are left
blank.
As AMIBCP won't open the BIOS file for this board, I cannot tell you
whether any brands of memory get special handling in the BIOS. In
some previous BIOS from Asus, certain model numbers of DIMMs get
their improperly coded SPD EEPROMS fixed by information that was added
to the BIOS.
In terms of the settings, I notice the BIOS has a "single/dual" channel
setting, and you might try that in single channel mode. Using
single channel mode seems to help boards that are marginal when operating
in dual channel mode. For example, I had some bad ram on an A7N8X-E, and
it would only run at maybe 185MHz in dual channel mode, and 200MHz in
single channel mode. My theory is, there is less electrical noise inside
the Northbridge, when only 64 bits are pumping at any one time, instead
of 128 bits dancing around. (I bet with three sticks of RAM, the board
was in single channel mode, and when the fourth stick appeared, the BIOS
probably automatically applied dual channel mode. That is why I bet
setting it to single channel will give temporary relief.)
The purpose of all the playing around, is to try to ascertain whether
this is a BIOS problem, or is just the usual signal integrity problems
that are all part of a multidrop SSTL terminated memory bus.
As for the Asus memory list in the manual, it gives some pretty crazy
information. For example, there are some sticks, that the Asus list
claims only run when you use four sticks, but not two sticks or one
stick. That makes no sense at all. I can understand the list saying
one or two sticks work, but not more, but not the reverse, as four
sticks is harder to run electrically than two sticks or a single
stick. After all, people who overclock, use a single stick of RAM
for a reason. So, don't pay too much attention to the Asus list -
it is much better to search private forums, for signs that particular
memory chips aren't compatible with a Northbridge. And digging up that
info can take a lot of your time. It took me about a week of evenings,
reading posts, before I had enough info to buy my current batch of
RAM, and so far I haven't been disappointed with my purchase (haven't
overclocked it yet).
HTH,
Paul
