Should I max my FSB?

[raptorx]

I've been running my system (Q6600) at 9 x 390 FSB for 3.51GHz.

[NickN]

Overclocking is an art and a science and it goes far past FSB and multipliers. Maxing out the FSB is not needed unless your memory simply wont hold to certain formula criteria, then FSB increases do help but you eventually reach a point where it works against you

On DDR2 systems, the most efficient FSB is 400-425. On DDR3 its 450-465. Those values depend on certain clocking formulas being in place. Later this year that will switch to 500 with DDR3

At DDR2 1000, this is the best clock:

400FSB @ 5:4 memory Divider (STRAP) @ DDR2 1000-1066 and CAS 4-4-4-10 @ tRD6

Next up DDR2 1200 400FSB @ 3:2 memory Divider = (266 STRAP) @ DDR2 1200 and CAS 5-5-5-12 @ tRD6

That depends on the system being set up EXACTLY for memory CAS 4/DDR2 1000 or CAS5 DDR2 1200. If the memory wont do CAS4/5 @ trD6 the above wont help and FSB must be increased to compensate.

This is why the memory purchase is so important. its not just the memory SPEED, its the CAS Latency. Once you find the lowest CAS you can run at the highest memory speed, then and ONLY THEN do you raise the multiplier and see how far the CPU goes

You are ALSO required to stress test for consistant stability over many HOURS not minutes


If you are interested in reading about such things and how they affect FSX... try this thread:


http://forums.avsim.net/dcboard.php?az= ... &mode=full


Also, see the 3 chart in on this page... best picks marked in green with lowest CAS and tRD

http://www.anandtech.com/mb/showdoc.aspx?i=3208&p=9

[raptorx]

I understand the art & science part.  All I can do now is ask questions, gain knowledge, and test.  I'm also running my stability tests for 9 hours minimum.

I have 4gigs Kingston HyperX and a P35 motherboard, I'm not sure I want to volt beyond 2.2 vDIMM as I don't want to cook this stuff (just yet).  So I'm running at relaxed timings, CAS 5-5-5-15, and my motherboard dividers force me to underclock from the rated (1066) speed @ the FSB I'm running.

By the way, I have 2 Gb of DDR2 1200 Transcend Xram lying around.  How do you think that would compare to 4 Gb Kingston @ DDR2 975?

Thanks Nick,
Jim

[Slotback]

According to sisoft sandra my memory bus bandwidth is 12.53gb/s, FSB is 8.34GB/s.... would it make sence for me to lower the multi and up FSB?

Also, what is tRD?

[NickN]

[quote]I understand the art & science part.

[NickN]

According to sisoft sandra my memory bus bandwidth is 12.53gb/s, FSB is 8.34GB/s.... would it make sence for me to lower the multi and up FSB?

Also, what is tRD?

tRD is MCH READ DELAY

You can read about tRD and CALWI it here:

http://www.anandtech.com/showdoc.aspx?i=3239&p=7

[raptorx]

tRD is what the "performance level" feature controls, right?

[Slotback]

^ Yes.

According to sisoft sandra my memory bus bandwidth is 12.53gb/s, FSB is 8.34GB/s.... would it make sence for me to lower the multi and up FSB?

Also, what is tRD?

tRD is MCH READ DELAY

You can read about tRD and CALWI it here:

http://www.anandtech.com/showdoc.aspx?i=3239&p=7

Thanks Nick. And I change tRD in memset or, if my BIOS supports it, BIOS right?



So for me it would be -
4 x (1000/266) = 15ns. right? I wonder if my P35-DS3P could run with a performance level of 3 at this 266......

[NickN]

tRD is what the "performance level" feature controls, right?

Yes

The real name is MCH READ DELAY and newer motherboards (x48 and above) will call it that and also supply a MCH VOLTAGE setting as well.

With motherboards of the last year it is called "performance level'

[NickN]

^ Yes.

According to sisoft sandra my memory bus bandwidth is 12.53gb/s, FSB is 8.34GB/s.... would it make sence for me to lower the multi and up FSB?

Also, what is tRD?

tRD is MCH READ DELAY

You can read about tRD and CALWI it here:

http://www.anandtech.com/showdoc.aspx?i=3239&p=7

Thanks Nick. And I change tRD in memset or, if my BIOS supports it, BIOS right?



So for me it would be -
4 x (1000/266) = 15ns. right? I wonder if my P35-DS3P could run with a performance level of 3 at this 266......

[Slotback]

Are you telling me you are running tRD 4 stable right now?

Yes - I don't even know how to change it yet that's what memset sais.

What are all the settings associated with that... the current divider, memory speed, FSB, CPU speed, and I assume that is on the 266 STRAP

FSB: DRAM - 2:3
FSB - 266
CPU speed - 2400mhz
Strap - I think so.

4 x (1000/266) = 15ns.




And I change tRD in memset or, if my BIOS supports it, BIOS right? What does the auto do in memset? What does lock mch bar do?

[ThatOnePerson]

Interesting read

[NickN]

Are you telling me you are running tRD 4 stable right now?

Yes - I don't even know how to change it yet that's what memset sais.

What are all the settings associated with that... the current divider, memory speed, FSB, CPU speed, and I assume that is on the 266 STRAP

FSB: DRAM - 2:3
FSB - 266
CPU speed - 2400mhz
Strap - I think so.

4 x (1000/266) = 15ns.




And I change tRD in memset or, if my BIOS supports it, BIOS right? What does the auto do in memset? What does lock mch bar do?

AUTO maintains the timing and changes on both sticks at the same time, and also releases default chipset register keys for changes, .. ALL PRECHARGE TO REFRESH DELAY for one

Lock MCHbar is used to lock the chipset register when the application is closed. 965 chipsets require that, some chipsets dont. That feature wont be enabled if it does not have any use.

Benchmarks dont mean squat unless you know how to read them, especially bandwidth numbers

http://forums.avsim.net/dcboard.php?az= ... 8016&page=

[raptorx]

Holy crap there's a lot of reading there!  How in God's good name am I gonna cram all your years of experience into my brain? :-/  What the hell did I get a biochemistry degree for when I could have started out in college 20 years ago in computer science!  I would know all this stuff and my FSX would that much better!

-Jim