Few years ago before i knew much about computers, i upgraded my mothers RAM and I remember the Best Buy 'tech' people telling me i needed to buy her RAM modules in pairs. Now that my knowledge about PCs have increased, i know this is not always the case.

Question: Why did some MB manufacturers have banks of 2 or banks of 4? Thank God, my Dell is fairly new where i can install one at a time - but it leaves me wondering why someone didn't think of this before. My only guess is that it was a technology issue back then where it is not an issue now.

Different type of memory. RDRAM still needs to be installed in pairs while SDRAM and DDRRAM don't (usually). What you probably are thinking of was EDORAM which was where I came in, too.

It was indeed a technology issue. Pentium (1) motherboards used SIMMs (SINGLE inline memory modules), and had to be paired up to form a bank of memory. I had an old Pentium 133 board that had 8 slots for memory!!

Every motherboard I've seen since the first Pentium II motherboard has supported DIMMs (DUAL inline memory modules). As you can probably guess by the name, a DIMM can occupy an entire memory bank by itself. SDRAM (PC100, PC133) and DDR (PC2100, PC3200, etc...) memory modules are DIMMs.

Edit: oops, thanks Bob, totally forgot about RDRAM (never used it, never will, hehe)

max

SIMMS had a 32bit memory bus, so you needed two of them per bank to match the 64bit Pentium or AMD-K6 memory bus. DIMMS are 64bit devices so they need not be paired.

Shelly

Shelly as usual, your response was very succint and to the point. Thank you all for responding.