MONSTERBOX87

I bought two PC6400 RAM chips and I don't know what the PC6400 part actually means. Is it to say what series of speed the RAM is, or does it have something to do with the speed of the RAM?

fortyways

I believe PC6400 is DDR2 800MHz RAM, so yes it's a way of categorizing it by speed. If you're asking where they get the 6400 number from you'll have to wait until someone more knowledgeable replies.

Cromewell

The numbers are the maximum peak transfer speed in MB/s.

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reddevil6

yea thats what i thourt 6.4GPS.
but in duel channel it runs at 12.8GPS does it not.

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Cromewell

If you think about it, in this case, dual channel would be 2x6400MB/s or 12800MB/s

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Deviousmind

As i believe it to be DDR means, double data rate meaning if you put in a stck of 200mhz it is doubled and rated as 400mhz pc3200
so if you stick a 200mhz rated at DDR 2 its effectively mulitpling it by 4 so its 800mhz pc6400
as for the pc name i have been told it goes a little this theres never any more than "four" memory slots on a m/b so this is used as a "standard" for working out the pc number
if you have four ddr 400mhz sticks in your mobo then its
200mhz x 2 = 400mhz said ram speed
400mnz x 4 mem slots = 1600
and as the transfer rate is 2mb/ sec this is muliplied to get 3200 i.e pc3200
so if you have DDR 2 at 800mhz its like this
200mhz x 4 = 800mhz said ram speed
800 x 4 memory slots = 3200
as the the transfer rate is still 2mb/sec this muliplied to get 6400 i.e. pc6400
some still go back to older ram types as the pc 8500, this worked this way
266mhz x 4 = 1064/1066 said ram speed
1066 x 4 mem slots = 4264/4200
as the transfer rate is 2mb/second this muliplied to get 8400 i.e. pc 8400
hope this helps but depends on mhz

Cromewell

Huh?

To go from the DDR rate to the MB/s rate (or PC #) you multiply by 8. To do the math you take the DDR rate (frequency * 2, so 200MHz * 2 for PC3200/DDR400) * 64 (64 bit channel) and divide by 8 (8 bits per byte).

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