I am looking at replacement PCs at work and the 2 front-runners have similar specs excepting the configuration of the DDR2 800 RAM, one being single channel t'other being dual channel. In words of one syllable can someone explain what practical advantage 2Mb of dual channel RAM would have over a similar amount configured as single channel?
Dual channel RAM - which must be fitted as matching pairs of modules, into the correct sockets - means that RAM accesses can be interleaved between the two modules. This cannot make it twice as fast - but in practice about 1.5 times as fast as single channel.
It doesn't make it 128bit memory - it means it can overlap memory accesses between the two modules - not the same thing at all.