The whole ratio deal

[Dooby]

Ok... Im new to overclocking and keep hearing about this 5:4, 1:1, etc ratios... how to I find out what I am running at? What does it all mean? Is it motherboard dependent? If so, me gots a P4C800 with a 3.2Ghz, and ocz pc4000 gold mem... Thanks and straighten me out!!!!!!!!

[Duvie]

The ratios are the dividers in which the memory speed is set in relationship to the fsb of the system.

The 1:1 ratio will be the default and will match the cpu fsb....For example the p4 3.2c will have a 200fsb at default and therefore the memory at 1:1 will also have a 200fsb for 400mhz ddr or pc3200 standard. At this point you are way underclocking the ram. So jack the timings to most aggressive and start to oc as much as possible. Using all of your rams potential is highly impossible with a 3.2c and its 16x multiplier.

The 5:4 ratio would take 200fsb/5 for 40 then times it by 4 for 160fsb for memory. That 160fsb constitutes to 320mhz ddr and less the pc2700 standard. This is not the way you want to go with the pc4000. leave it at 1:1.



From what I have seen in terms of 3.2c chips it is highly unlikely you can oc much better then 225-235 range if you are lucky. In this case the best you will run your ram is 450 to 470mhz ddr which is still underclocking the ram.

[Dooby]

that helps a lot! thanks! so 5:4 is not the way to go for me if I understand correctly...

[Duvie]

That's right!!! 1:1 all the way and with the lowest timings you can set. Your ram will be coasting....500ddr would have worked with a 2.4c or a 2.6c since 250fsb is more likley when ocing those chips, but no 250 with the 3.2ghz chip cause that would be 4ghz and I think you would need some serious water cooling and a bit of luck....

[oldfart]

There has been a lot of posts/discussion on the ratio thing. Its not quite that simple.

DDR speed AND timings matter. To run very high DDR speeds, you have to run slow timings with the current crop of PC3700 - 4000 ram. You can get the same or sometimes better performance running a lower DDR speed using a ratio and faster timings.

Its like a car

3000 RPM in 4th gear = 70 MPH
2500 RPM in 5th gear = 70 MPH

It depends on what CPU/mobo/FSB/ram combo you use.

With a 3.2C, you will not be going very high in the FSB speed and won't need a ratio. Get some ram that can run tight timings.

[Duvie]

Originally posted by oldfart
There has been a lot of posts/discussion on the ratio thing. Its not quite that simple.

DDR speed AND timings matter. To run very high DDR speeds, you have to run slow timings with the current crop of PC3700 - 4000 ram. You can get the same or sometimes better performance running a lower DDR speed using a ratio and faster timings.

Its like a car

3000 RPM in 4th gear = 70 MPH
2500 RPM in 5th gear = 70 MPH

It depends on what CPU/mobo/FSB/ram combo you use.

With a 3.2C, you will not be going very high in the FSB speed and won't need a ratio. Get some ram that can run tight timings.

A lot to do with quirky bioses of indivdual mobos some sticks cannot do the same speed and timings in all boards...

for the most part tohe theory is that simple and is the basic jist of the concept of ocing with the fsb...