Simviation Forum - Should I max my FSB?

Apr 12^th, 2008 at 7:43pm

raptorx Offline
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There's too much confusion...
San Diego, CA

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I've been running my system (Q6600) at 9 x 390 FSB for 3.51GHz. Memory is running at 975MHz DDR2 (rated 1066). GA-P35-DS4 has limited dividers. I was wondering if I should try reducing the multiplier to 8 and running around 440-450 FSB with memory running closer to 1066?

I tried 9 x 400 but my Everest memory benchie's were significantly better at 9 x 390, I assume that's because of strapping. So I would need to get well above 400 FSB to make it up, right? Should I just keep it at the setting w/the higher multiplier?

-Jim

Rampage II Gene, i7 965 4GHz
Mushkin Redline DDR3 1600
XP x64 SP2
ASUS Matrix GTX285

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Reply #1 - Apr 13^th, 2008 at 12:13pm

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

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=show_topic&forum=197&topic_id=37210&mode=...

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

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Reply #2 - Apr 13^th, 2008 at 2:38pm

raptorx Offline
Colonel
There's too much confusion...
San Diego, CA

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Posts: 434

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

Rampage II Gene, i7 965 4GHz
Mushkin Redline DDR3 1600
XP x64 SP2
ASUS Matrix GTX285

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Reply #3 - Apr 14^th, 2008 at 4:40am

Vodka Burner Ex Member

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?

« Last Edit: Apr 14^th, 2008 at 6:16am by N/A »

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Reply #4 - Apr 14^th, 2008 at 9:22am

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

raptorx wrote on Apr 13^th, 2008 at 2:38pm:

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

By design 2GB will always clock better than 4 but unfortunately you lose the >2GB advantages so in some cases its 6 of one, 1/2 dozen of the other

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Reply #5 - Apr 14^th, 2008 at 9:25am

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

Quote:

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

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Reply #6 - Apr 14^th, 2008 at 10:46am

raptorx Offline
Colonel
There's too much confusion...
San Diego, CA

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

Rampage II Gene, i7 965 4GHz
Mushkin Redline DDR3 1600
XP x64 SP2
ASUS Matrix GTX285

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Reply #7 - Apr 15^th, 2008 at 2:13am

Vodka Burner Ex Member

^ Yes.
NickN wrote on Apr 14^th, 2008 at 9:25am:

Quote:

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......

And lower trd will require more volts? Is that why OCers often need to add more to the NB? Also, what's the diferance between diferant straps?

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Reply #8 - Apr 15^th, 2008 at 8:51am

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

raptorx wrote on Apr 14^th, 2008 at 10:46am:

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'

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Reply #9 - Apr 15^th, 2008 at 8:54am

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

Quote:

^ Yes.
NickN wrote on Apr 14^th, 2008 at 9:25am:

Quote:

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......

And lower trd will require more volts? Is that why OCers often need to add more to the NB? Also, what's the diferance between diferant straps?

Strap, quite simply, is the latency on the northbridge in association with the FSB.

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

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

The reason I ask is because i have only known 2 people who have hit tRD 4 on a correct, high end memory overclock.

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Reply #10 - Apr 16^th, 2008 at 1:14am

Vodka Burner Ex Member

Quote:

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.

Quote:

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?

« Last Edit: Apr 16^th, 2008 at 2:48am by N/A »

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Reply #11 - Apr 17^th, 2008 at 10:56am

ThatOnePerson Offline
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The Blue Planet

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Interesting read Wink

&&"Float like Pissed-Off Butterfly, Sting like Bad-Ass Bee."

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Reply #12 - Apr 17^th, 2008 at 5:18pm

NickN Offline
Colonel
FSX runs fine... the problem
is you or your system

Posts: 6317

Quote:

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.

Quote:

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=show_mesg&forum=197&topic_id=37210&mesg_i...

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Reply #13 - Apr 17^th, 2008 at 11:35pm

raptorx Offline
Colonel
There's too much confusion...
San Diego, CA

Gender:
Posts: 434

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? Undecided

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

Rampage II Gene, i7 965 4GHz
Mushkin Redline DDR3 1600
XP x64 SP2
ASUS Matrix GTX285

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