memory speed equation

[Jo-Jo]

can someone please post the equation for fsb?

example, if my ram is at 246 fsb, 5:4, what is my ddr, and at what is the pc rating?

thanks

ddr400=pc3200

[JKeefe]

The ratio is of FSB speed (not quad-pumped) to memory speed (not doubled for DDR). So, at 1:1, 200 FSB = 200 memory (DDR400), 250 FSB = 250 memory (DDR500), etc.

At 5:4, 200 FSB = 160 memory (DDR320), 250 FSB = 200 memory (DDR400)

At 3:2, 200 FSB = 133 Memory (DDR266), 250 FSB = 166 memory (DDR333).

PC Ratings are as follows:
DDR266: PC2100
DDR333: PC2700
DDR400: PC3200
DDR433: PC3500
DDR466: PC3700
DDR500: PC4000

[Sophisticated]

Originally posted by JKeefe
The ratio is of FSB speed (not quad-pumped) to memory speed (not doubled for DDR). So, at 1:1, 200 FSB = 200 memory (DDR400), 250 FSB = 250 memory (DDR500), etc.

At 5:4, 200 FSB = 160 memory (DDR320), 250 FSB = 200 memory (DDR400)

At 3:2, 200 FSB = 133 Memory (DDR266), 250 FSB = 166 memory (DDR333).

PC Ratings are as follows:
DDR266: PC2100
DDR333: PC2700
DDR400: PC3200
DDR433: PC3500
DDR466: PC3700
DDR500: PC4000

and if you need to know the equation in details here goes

for 5:4 the equation is - FSB Divided by 5 x 4 = Memory speeds x 2 for full memory speed...for example

250FSB Divided by 5 x 4 = 200MHz x 2 = 400MHz (pc3200) same equation for the other dividers....wanna kno how to get the pc ratings??? its memory speed x 8 = rating for example....400MHz x 8 = 3200...same goes for the other speeds

[Jo-Jo]

Originally posted by Sophisticated


and if you need to know the equation in details here goes

for 5:4 the equation is - FSB Divided by 5 x 4 = Memory speeds x 2 for full memory speed...for example

250FSB Divided by 5 x 4 = 200MHz x 2 = 400MHz (pc3200) same equation for the other dividers....wanna kno how to get the pc ratings??? its memory speed x 8 = rating for example....400MHz x 8 = 3200...same goes for the other speeds

so pc3200 @ 246fsb, with the 5:4 divider is still at spec. the ram isnt overclocked?

but at 215fsb, with 1:1, it being overclocked to almost ddr433/pc3500?

thanks

[Sophisticated]

correct..at 246FSB it is a tad bit underclocked at 5:4..1:1 divider @ 215FSB is overclocked...