In article ,
P2B wrote:
Anyone know what causes erratic RAM detection on P2B series
motherboards, particularly at 133Mhz FSB?
I've never had any problems running 768MB (3x256MB) on my P2B-DS boards,
and one is fully loaded with a gig.
I recently purchased a bunch of used 256MB sticks, mostly Micron but a
few are other brands, with the intent of upgrading our single processor
P2B systems from 256 to 512 or 768MB.
I tested it all in matched pairs on a modified P2B-AE running a P3-S
1.4Ghz CPU (133Mhz FSB) - configured the BIOS for 222 timings regardless
of SPD, and ran memtest86 3.0 in all tests mode for at least 5 full
passes on each pair.
All testing completed without a single problem or error, but when I
install in the target systems I encounter nothing but grief :-(
On one P2B-AE system, the BIOS only detects either 64MB or 128MB from
cold start when 512MB is installed, and it won't POST on reset - has to
be powered off to try again. I tried all the tested pairs, and also
mixed brands, but couldn't get it to detect more than 128MB when both
RAM slots were filled - not even at 100Mhz FSB and 333 timings - but
this one has the same board revision and BIOS as the test system that
detected 512MB every time!
Similar story on a P2B-S machine, although I eventually found a
mixed-brand pair that works properly in this system - but no way will it
detect three sticks.
RAM voltage on all systems is within 100mV of 3.4V, the only significant
difference is Tualeron processors in the target systems vs. a P3-S in
the test system - but that seems unlikely to affect RAM detection.
My P3B-F runs perfectly with 3x256MB PC133 modules from Crucial
at 100MHz FSB, but at 133MHz FSB (the CPU is a 1.26GHz Tualatin P3)
there are intermittent read errors detected both by memtest86 and
by running heavy application loads. 2x256MB works reliably at 133MHz,
but unfortunately I need all the memory I can get.
I guess I should have bought registered modules :-(
/Mikael
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Mikael Pettersson )
Computing Science Department, Uppsala University
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