Re: Over 2.5 GB ram problem
On 7/13/2013 7:06 PM, Gary Roach wrote:
> On 07/13/2013 03:17 PM, Stan Hoeppner wrote:
>> On 7/13/2013 3:09 PM, Gary Roach wrote:
>>> And don't
>>> forget that as the BIOS self tests it only finds 2.8 GB even though all
>>> 4 memory chips are detected.
>> Finally we're getting somewhere.
>>
>> The entire length of this thread I was assuming you were seeing 4GB at
>> POST. You never stated otherwise, and ASSURED us the system had 4GB of
>> RAM. It doesn't. There are 4GB of DIMMs apparently installed, but
>> that's much different than the "system having 4GB".
>>
>> What you have is mismatched memory. Read the DIMM specs in that manual
>> PDF. The board supports DDR 200/266, and supports single and double
>> sided DIMMs, BUT not in all density (DIMM size) and frequency
>> combinations.
>>
>> I.e. when all 4 slots are filled you must have a specific combination of
>> DIMM sizes and "sidedness" for the board to recognize and use all 4GB.
>> Read the manual and look at all 4 of those DIMMs and you'll identify the
>> problem. The fix will require that you acquire some different memory,
>> either 2 or all 4 of the sticks.
>>
> Sorry Stan. Ain't so. There 4 identical Kingston 1GB modules all with
> the same model number. I very carefully purchased these after making
> sure that they were compatible with the motherboard and processor. Not
> the problem.
I find it ironic that your DIMMs won't configure properly, yet you're
cock sure that the problem isn't the DIMMs. I find it equally ironic
that you've taken a condescending tone with me, someone who has
forgotten more about hardware than you'll ever know.
The fact that the DIMMs are the same model (matched) doesn't matter one
iota if they are the wrong DIMMs, or if one is defective. The fact that
any two will configure properly but all 4 won't tells us without zero
doubt that the problem is one of these three things:
1. The DIMMs in a set of four don't meet the motherboard requirements.
2. You have a faulty DIMM, or
3. You have a defective motherboard.
And yes, a DIMM can work in a pair just fine even if defective, but not
work in 4s. The same can be true if the DIMMs are the correct spec for
the board in a quad configuration. It depends entirely on the nature of
the defect and the resulting failure mode. For instance, when running a
pair of DIMMs not all of the address lines are active on each DIMM.
When you run all 4, more of the address lines are used, or all of them
are. This depends on the DIMM design and the system's DIMM slot count,
and maximum memory size. The first thing you need to do at this point,
despite the fact that you are absolutely positive you bought the right
memory, is verify that the DIMMs are indeed the required configuration.
Which is:
1024MB, Double Sided, 512 Mbit chip density, 64Mx8/64Mx8 front/back, 8
chips per side, 16 total. This is the ONLY configuration of 1GB DIMMs
supported by this board. If you have single sided 1GB DIMMs that they
don't meet the specification. However they may still work with only two
plugged in.
If you actually do verify this is the configuration of these DIMMs, the
second thing you need to do is test in groups of 3. This may tell you
if one of the 4 has an addressing defect. You will know this if one and
only one combination of 3 out of 4 shows a different total size than the
other combinations of 3.
The third and final thing to test is the DIMM slots in groups of 3. In
the same manner as above, this should tell you if one of the 4 slots has
an addressing defect. It could be due to a bent/damaged contact in the
socket, a cracked board trace, or a bad solider joint between the DIMM
socket and the substrate. The former should be relatively easy to spot.
The latter two you won't be able to see.
> To clarify, the BIOS lists 4, 1GB memory modules under the
> memory setup part of the BIOS setup screen. During the boot process the
> memory check is visible ratcheting up to 2.8 GB and stops.
This is evidence of one of the 3 things above.
> The boot
> process then continues. Yes I did swap the modules around and they all
> seemed to work fine. If I put 2 of them in the system the whole 2 GB is
> visible. I can do this in any combination.
This isn't unusual. Again, see above.
> I just noticed that the manual states that AGP and PCI memory needs are
> all above 3GB so I should have at least 3 GB.
>
> I still appreciate the thought.
You'll appreciate the thought more after you actually listen to me and
troubleshoot this to conclusion, instead of blindly assuming things are
OK when they're obviously not, assuming you know something as fact, when
you don't.
Something very important here that you're failing to understand is that
I've come across your exact problem at least a couple dozen times over
the past 20 years. In every case the cause has been DIMMs not meeting
the board requirement, or bad addressing logic in one of the DIMMs. And
I shouldn't be using the term "DIMM" here exclusively. I first saw this
problem with SIPPs on 80286s, and I've seen it with SIMMs as well. So
I've seen it with every memory module type going back to the early 90s.
In the 80s there were no socketed DRAM modules--the 8088/8086 XT clones
used full length DRAM 8 bit ISA boards. When one of these went bad, you
had an expensive repair, ~$500, for a 128KB board. Yes, 128 kilobyte,
the same size as the L1 cache on current AMD64 CPUs cores. And yes, I'm
and "old fart", at 42, given the average age on this list.
Drop your "I know it all" attitude and work with me, and we'll get this
figured out. It's hardware, not rocket science. I've seen and fixed
pretty much every problem one could encounter with x86 PC hardware.
--
Stan
Reply to: