Intel Overclocking Redefined - Interesting P965 / 975X Secrets - Page 3 - Overclock.net

pauldovi · 01-04-07

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.

Intervention · 01-04-07

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.

**adam144** · 01-04-07

Great find, lots of info

**Burn** · 01-04-07

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*

Intervention · 01-04-07

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.....

**Burn** · 01-04-07

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

pauldovi · 01-04-07

Quote:

Originally Posted by Burn

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*

Here it goes.

Your north bridge has an internal clock speed and latencies just like your CPU and memory. The FSB of your north bridge can be found by dividing your original CPU multiplier by your set CPU multiplier and then multiplying by your FSB.

So if you are running a E6600 (266 * 9) at 400Mhz x 8 your NB FSB is:

(9 / 8) x 400 = 450Mhz FSB (1800Mhz Total)

Just like your memory may be able to run at 4-4-4-12 at 1000Mhz but needs to run at 5-5-5-15 at 1200Mhz, your north bridge has a series of latencies which it must adjust in order to maintain stability at its FSB. These latencies seem to play a far more significant role in system performance than memory latencies.

Intel has predefined specific latencies at specific NB FSB speeds. They are referred to as straps. There is a strap for when the NB FSB is 1066Mhz and under, 1333Mhz FSB and under, 1600Mhz FSB and under, ect. When you go from the 1066Mhz FSB strap to the 1333Mhz FSB strap, the north bridge's internal latencies loosen to allow for greater stability.

ASUS has redefined the NB strap so that the 1333Mhz FSB strap does not come into effect until 401Mhz FSB (1604Mhz). Other perimeters of straps are someone unknown.

Tony, the guy who pretty much figured all this out has since been hired by OCZ (they were impressed). He is now a lobbyist trying to get ASUS and other major motherboard manufacturers to give the end user the control of when straps start.

There are 2 ways to beat the NB strap:

1. Boot to windows in the 1066Mhz strap and then use Clockgen to increase your CPU's FSB. You can then get to a much higher FSB while maintaining the 1066Mhz strap simply because the BIOS does not adjust the north bridge's latencies in real time.
2. Get a X6800 or QX6700 (or even a ES chip). To the north bridge, you are always at a default multiplier with a Extreme Edition processor. This allows you to set a much lower or higher multiplier without the NB FSB being effected.

Intervention · 01-04-07

Thats my understanding of it. After reading a few pages of XS, it can make pretty big changes from fsb-395 to fsb-405.

Ihatethedukes · 01-04-07

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).

Not so much as you think...

http://www.xtremesystems.org/forums/...d.php?t=125463

**Burn** · 01-04-07

Quote:

Originally Posted by pauldovi

Here it goes.

Your north bridge has an internal clock speed and latencies just like your CPU and memory. The FSB of your north bridge can be found by dividing your original CPU multiplier by your set CPU multiplier and then multiplying by your FSB.

So if you are running a E6600 (266 * 9) at 400Mhz x 8 your NB FSB is:

(9 / 8) x 400 = 450Mhz FSB (1800Mhz Total)

Just like your memory may be able to run at 4-4-4-12 at 1000Mhz but needs to run at 5-5-5-15 at 1200Mhz, your north bridge has a series of latencies which it must adjust in order to maintain stability at its FSB. These latencies seem to play a far more significant role in system performance than memory latencies.

Intel has predefined specific latencies at specific NB FSB speeds. They are referred to as straps. There is a strap for when the NB FSB is 1066Mhz and under, 1333Mhz FSB and under, 1600Mhz FSB and under, ect. When you go from the 1066Mhz FSB strap to the 1333Mhz FSB strap, the north bridge's internal latencies loosen to allow for greater stability.

ASUS has redefined the NB strap so that the 1333Mhz FSB strap does not come into effect until 401Mhz FSB (1604Mhz). Other perimeters of straps are someone unknown.

Tony, the guy who pretty much figured all this out has since been hired by OCZ (they were impressed). He is now a lobbyist trying to get ASUS and other major motherboard manufacturers to give the end user the control of when straps start.

There are 2 ways to beat the NB strap:

1. Boot to windows in the 1066Mhz strap and then use Clockgen to increase your CPU's FSB. You can then get to a much higher FSB while maintaining the 1066Mhz strap simply because the BIOS does not adjust the north bridge's latencies in real time.
2. Get a X6800 or QX6700 (or even a ES chip). To the north bridge, you are always at a default multiplier with a Extreme Edition processor. This allows you to set a much lower or higher multiplier without the NB FSB being effected.

Sorry to make you type so much

An excellent explanation- Thank you very much!

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Intel Overclocking Redefined - Interesting P965 / 975X Secrets

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