System concerned, secondary system in signature.
I've come across some odd behaviour which when installing additional RAM which, as far as I can understand, must be related to the motherboard (Abit KT7A), which according to specs is supposed to be capable of addressing a maximum of 1Gb RAM (PC133), distributed over three(!
RAM slots, which would leave us with the possible combinations of 2 x 512 or 1 x512 + 2 x 256.
Now, much to my joy, I came across a stick of 512Mb PC133 recently, which I promptly had replacing the stick of 128Mb RAM on the motherboard, leaving it fully populated with 2 x 256 and 1 x 512. Fully populated, but definitely not fully operational. At first, Prime95 reported errors within a matter of minutes. Testing with dedicated RAM-diagnostics software, however, did not report any errors. And every combination, stick and slot-wise, worked perfectly as long as I did not populate all three slots. With one exception; when populating the third slot with 64Mb of PC100 no stability issues were reported. Eventually, the system wouldn't even boot into WinXP (or Win98 - or Mandriva) with all three slots populated (the previously mentioned PC100 excepted) and started reporting all sorts of errors, one more inspired than the other (some of which HDD-related, which in my experience very well could be related to flakey memory-addressing).
At present, I'm running the system with a total of 756Mb RAM (512 + 256) and it's perfectly stable, more stable actually, than it was when populated with 256 x 2 + 128. With that setup it didn't tolerate any overclocking at all, but now it seems to run smoothly when moderately overclocked to 1 333Mhz (I better mention that I'm overclocking using the multiplier settings here, NOT the FSB, which is unchanged at 133Mhz). At least according to Prime95.
One possible explanation would be that there's a frequency limit (3 slots at 100Mhz, 2 slots at 133Mhz), but I find that somewhat unlikely, given my previous experiences. Can't find much info on it though.
And yes; some of the RAM-sticks (some of which has been in the rig since I got it) reports "reduced self refresh (.5x)". Anyone like to comment on that? I haven't got a clue myself. Since the 512Mb-stick reports this, I've combined it with a 256Mb-stick that reports the same values. Better safe than sorry
Primary: MOBO: Asus A7V600. CPU: AMD Athlon XP (Barton firstname.lastname@example.orgGhz). GPU: ATI RADEON 9200SE (128MB). RAM: Apacer PC2700 (512MB), Kingston PC3200 (1Gb) = 1.5Gb. HDD: Seagate Barracuda (S-ATA 200Gb), WD CaviarSE (S-ATA 320Gb). Cooling: Front (inlet); 120mm fan, back (outlet) 120mm fan, HSF Thermaltake Big Typhoon. PSU: 430w (Seasonic), +12V = 14A + 15A, +5V = 30A, +3,3V = 30A. <spa