Good find!

 

did you read this

i read up on this a while back, its very interesting stuff, just through this in with what you have and make a faq or something like that for this site

edit: for this same reason is why people hit apparent fsb walls at 395 or so and have to jump over 400 to like 402 or so with certain mobos

 

so 450 x 8 (which I currently run at) is no faster than 400 x9, perhaps slower?

And to notice an improvment 460 x 8 would be my best option?

 

What seems to be the best at the moment is stock multiplier and a 400Mhz FSB or greater than 460Mhz FSB (at stock multi).

You see, you can find the speed of the NB by taking your default multi and dividing it by whatever you have it set by and then multiply by your FSB.

So - 9/8 * 450 = 506.25Mhz (2025Mhz FSB for the NB)

It seems like the FSB strap will come into effect at a lower FSB when using a lower than default multiplier.

The 1333Mhz strap is suppose to start at 333Mhz FSB. However, ASUS manipulated the strap to allow to go to 400Mhz FSB before the 1333Mhz strap latencies kick in.

 

Other than super pi, does it have an effect on any realword situations?

 

thread

yeah if you read to the bottom of that thread it shows ( i think) that a higher fsb say 500 or so coupled with a decrease of 1 from the stock multi gives you the best results, this can give yousome really good stuff with the 6300/6400

i would test more but my mobo has locked multi's

 

Rep +1 Nice. Very Nice. I did notice a lack of superpi progress after about 3.6Ghz after looking at the 1M superpi bench thread.

I attributed it to the same principle that drag racers succumb to. A 500HP car runs in the 11ish range in the 1/4 mile but a 1000hp car is only in the 9ish range. Twice the power, only about 1/4 the speed increase.

Now I know it might just be the latencies of the strap.

 

Quote:

Originally Posted by lightsource Other than super pi, does it have an effect on any realword situations?

Yes, this results in significant performance and stability changes in your system.

Quote:

Originally Posted by Ihatethedukes Rep +1 Nice. Very Nice. I did notice a lack of superpi progress after about 3.6Ghz after looking at the 1M superpi bench thread. I attributed it to the same principle that drag racers succumb to. A 500HP car runs in the 11ish range in the 1/4 mile but a 1000hp car is only in the 9ish range. Twice the power, only about 1/4 the speed increase. Now I know it might just be the latencies of the strap.

That is a good analogy, however it has nothing to do with this. You see, what you are referring to is the law of diminishing returns. The more you put into something the less you get out of it.

What effect that is happening in the P965 / 975X is the north bridge is increasing its latencies after specific FSB levels in order to remain stable. At stock settings (Intel defined) the north bridge will increase latencies at 1066Mhz, 1333Mhz, and 1600Mhz FSB levels within the northbridge. However, ASUS has reconfigured its motherboards so that you can go to the 400Mhz FSB level while maintaining the 1066Mhz FSB latencies within the north bridge. However, once you reach 401Mhz FSB, the 1333Mhz FSB strap kicks in and you get significant north bridge latencies.

 

I'm gonna test this idea when I get home on my DFI for you and see if it encompasses that board as well.

 

Very interesting.

Looks like the often slated overclocking softwares have a purpose after all

especially ClockGen

 

Quote:

Originally Posted by Ihatethedukes I'm gonna test this idea when I get home on my DFI for you and see if it encompasses that board as well.

DFI will likely have different FSB straps than ASUS.

 

Pauldovi

Have you done any of your own testing using Clockgen? I'm thinking of downloading it and wonder if its any good

 

This newly discovered info also shows why 410Mhz FSB is more stable than 390Mhz for a lot of people.

@ Joeking78. I am going to wait for my P5B (gets here tomorrow) before I test thing. However, there are plenty of people who have run this on their system with the exact same results.

From my interpretation, 400Mhz FSB with the default multiplier and as high of a memory speed as possible will be the best performance for people who can't go higher than 500Mhz FSB. For people with X6800 and QX6700 the multiplier part is null, because the NB detects any multiplier as default.

Edit: There is a big push to get the BIOS engineering to give the NB strap control over to the end user. That would allow up to define where the NB changes latencies.

 

So what are you saying...

400x7 = better than 434x7

Or are you saying to set 400x7 in BIOS and go into ClockGen and set 434x7.

 

It also shows why the eVGA 680i has so many 'dead spots' in its FSB range.

 

Quote:

Originally Posted by Ihatethedukes It also shows why the eVGA 680i has so many 'dead spots' in its FSB range.

EVGA 680i works entirely different than P965 / 975X

@ Lightsource: Yes, 400 x 7 is better than 437 x 7. Just do some Super Pi tests with it. Clockgen will be inherently less stable because you are working on the lower strap, but that is the best way to go to get 437Mhz (although it seems there is no chance at getting more than 10-15Mhz FSB from clockgen).

 

Quote:

Originally Posted by pauldovi EVGA 680i works entirely different than P965 / 975X @ Lightsource: Yes, 400 x 7 is better than 437 x 7. Just do some Super Pi tests with it. Clockgen will be inherently less stable because you are working on the lower strap, but that is the best way to go to get 437Mhz (although it seems there is no chance at getting more than 10-15Mhz FSB from clockgen).

All right, what about in F@H? Faster WU's?

 

http://www.bleedinedgesupport.com/oc...ad.php?t=23803

 

Very interesting topic, good find.

I ahve one small kinda off topic question. I never realized before hand that dropping to a lower multiplier will OC the northbridge. This makes me nervous as I was going to go form a multiplier of 9 to 8, and run maybe 430 x 8 as this will get me ddr2-1075 which I can do at 4-4-4-12. Would this push my Northbridge too far, would I need better cooling? I know its off topic, but were talking about the northbrige anyways, so whay not.

 

Quote:

Originally Posted by Intervention Very interesting topic, good find. I ahve one small kinda off topic question. I never realized before hand that dropping to a lower multiplier will OC the northbridge. This makes me nervous as I was going to go form a multiplier of 9 to 8, and run maybe 430 x 8 as this will get me ddr2-1075 which I can do at 4-4-4-12. Would this push my Northbridge too far, would I need better cooling? I know its off topic, but were talking about the northbrige anyways, so whay not.

No, it is very much on topic.

From my understandings of things, you would have a 484Mhz NB FSB (1935Mhz NB FSB Total) That would put you in the 1600Mhz NB strap, which would give you poor performance compared to 400Mhz (9 multi). You want to try to stick to a 400Mhz FSB, stock multi, and as high of memory speed as possible. Tony has been working hard to get ASUS to release a BIOS where we can manual set the NB strap. That way you could set the 1333Mhz strap to say 1936Mhz and be great with your setup. Although that would require some increased voltage in the north bridge to keep it stable.

 

Thank you!, it now makes a little more sense. I had been debating switching to a lower multiplier, but now I see thats not the best move.

 

Great find, lots of info

 

Paul, is there any way you could explain what a NB Strap is? I have googled all over and can't find what it is/does.

*Sheepish nod*

 

My basic understanding is that there are built in steps for the NB latencies. Under 400mhz fsb, your on strap "A", However, stray to 401, and your on strap "B" with much higher latencies, thus giving far less perfomance.

^^^my very basic understanding of the topic, could be wrong.....

 

I see. So it's a mini-set of "RAM timings", but for a northbridge? I see..Thanks!