Power Supplies... which is better?

[imported_IslandTechie]

ok techies, im putting together a rig and now need to figure out what power supply to get.

the rig will have an amd64 3500+, 512mb x 2 ddr400, 2 x 250gb sata (possibly 4 in the future), dvdrw, dvdrom, cdrom, case fans galore, some lights, fdd, maybe a hdd cooler or two, ati 9800 pro.

i was looking at an antec true550w but also came across a thermaltake 680w. i know the 680 is overkill but it has all the connectors you could need, including pci-e (so i guess its future proof if i dont go nforce4 just yet), and an adapter to go from 20 to 24 or vice versa (dont remember).

i was looking at some posts regarding power supplies and everyone is saying to check the 12v rails. what is that?

i think the antec true550 has 24a 12v rails and the thermaltake has 22a 12v rails. what does that mean?

please explain.

 

[meltdown75]

the different rails handle different components. i'm sure there is a thread explaining which handles what somewhere around here. bigger is better. so assuming those 2 PSUs are in the same price range and all things being equal, it would be wiser to get the Antec. 680w is nuts, that's the largest wattage I have heard of so far. looks like you have a fair amount of stuff to power though and you can never have too much juice. out of those 3 optical drives though, you could definitely get rid of at least 1 and 2 unless you're burnin on the fly.