I've spent quite a bit of time over the past couple of weeks trying to learn about overclocking my system since I finally have time to mess with it. I've never overclocked anything before this which is why I want to understand as much of the underlying theory, principles and basics as possible.

So far I've tried to figure out my max FSB for the CPU at stock and max voltages and I will get back to work on the CPU after I figure out the memory which is where I am now. I'm trying to understand more specifically how timings vs. speed actually play out. For example, I can tighten my timings down to their lowest values except for TWTR (2, won't boot at 1) and get a max DDR2 clock of 306Mhz (612Mhz effective) at 1.9v or 343Mhz clock (686Mhz effective) at 2.2v. At the other end I can set the usual timing specs to 5-5-5-15-1T and the rest to auto and get a 458Mhz clock (916Mhz effective) at 1.9v or 506Mhz clock (1012Mhz effective) at 2.2v.

From reading at thetechrepository site they explained that you multiply the CAS value by the cycle time of your frequency to figure out the actual latency. To me this says that the latency is more representative/accurate of the time to do a single instruction. For example using my memory,

DDR2 800Mhz (400Mhz core) - Theoretical max bandwidth is 800Mhz x 8bytes/instruction = 6.4GB/s

DDR2 800Mhz (400Mhz core) @ CAS 5, latency = 2.5ns x 5 = 12.5ns/clock cycle

DDR2 800Mhz (400Mhz core) @ CAS 5 bandwidth = (1second / 12.5ns) x 16bytes/clock cycle = 1280MB/s = 1.28GB/s

There are two things that I want to point out to see if I am correct on a side note, the first being that DDR memory has a bandwidth of 16bytes per clock cycle. The second being instead of trying to figure out latency in nanoseconds and then figuring out what frequency that corresponds to it is easier to divide the core DDR speed by the CAS value to find what frequency is obtained when factoring in CAS and/or divide the max rated bandwidth by the CAS value.

I've read that basically if you can maintain similar latencies that faster rated ram will provide more bandwidth and I do not understand how. To me DDR 800 @ CAS 4 should be the same as DDR 1600 @ CAS 8 since their latencies are the same yet they both transmit 8 bytes twice per clock cycle. I think I understand that the 1600 works faster, twice as fast but isn't that negated since the CAS delay is twice as long? It all seems to make sense yet from all of the stuff I've read I feel like I am putting the pieces together wrong or I am missing something all together.

Edited by meltmanbob - 9/15/10 at 6:59am

So far I've tried to figure out my max FSB for the CPU at stock and max voltages and I will get back to work on the CPU after I figure out the memory which is where I am now. I'm trying to understand more specifically how timings vs. speed actually play out. For example, I can tighten my timings down to their lowest values except for TWTR (2, won't boot at 1) and get a max DDR2 clock of 306Mhz (612Mhz effective) at 1.9v or 343Mhz clock (686Mhz effective) at 2.2v. At the other end I can set the usual timing specs to 5-5-5-15-1T and the rest to auto and get a 458Mhz clock (916Mhz effective) at 1.9v or 506Mhz clock (1012Mhz effective) at 2.2v.

From reading at thetechrepository site they explained that you multiply the CAS value by the cycle time of your frequency to figure out the actual latency. To me this says that the latency is more representative/accurate of the time to do a single instruction. For example using my memory,

DDR2 800Mhz (400Mhz core) - Theoretical max bandwidth is 800Mhz x 8bytes/instruction = 6.4GB/s

DDR2 800Mhz (400Mhz core) @ CAS 5, latency = 2.5ns x 5 = 12.5ns/clock cycle

DDR2 800Mhz (400Mhz core) @ CAS 5 bandwidth = (1second / 12.5ns) x 16bytes/clock cycle = 1280MB/s = 1.28GB/s

There are two things that I want to point out to see if I am correct on a side note, the first being that DDR memory has a bandwidth of 16bytes per clock cycle. The second being instead of trying to figure out latency in nanoseconds and then figuring out what frequency that corresponds to it is easier to divide the core DDR speed by the CAS value to find what frequency is obtained when factoring in CAS and/or divide the max rated bandwidth by the CAS value.

I've read that basically if you can maintain similar latencies that faster rated ram will provide more bandwidth and I do not understand how. To me DDR 800 @ CAS 4 should be the same as DDR 1600 @ CAS 8 since their latencies are the same yet they both transmit 8 bytes twice per clock cycle. I think I understand that the 1600 works faster, twice as fast but isn't that negated since the CAS delay is twice as long? It all seems to make sense yet from all of the stuff I've read I feel like I am putting the pieces together wrong or I am missing something all together.

Edited by meltmanbob - 9/15/10 at 6:59am