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Belisarius

Core i7 Sandy-Bridge-E LGA2011 BCLK

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As title suggests, I am under the impression from an article such as this:

 

http://www.techarp.com/showfreebog.aspx?lang=0&bogno=422

 

that Core i7 CPUs have a BCLK of 133Mhz. Certainly my Core i7 960 runs at 133Mhz, just wondering about the new Sandy Bridge-E LGA2011 CPU's if they were the same frequency

 

Reason I ask is due to the QPI and RAM frequency. The other reason I ask is, I've seen 100Mhz thrown around as well and just wanted confirmation.

 

cheers

Edited by Belisarius

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The base clock is largely irrelevant, and can actually be changed in the BIOS. Both 3820 or 3930k for example have a 100mhz BCLK and use 36x and 32x multi respectively.. not including Turbo clocks. This can easily be increased to up to 125Mhz but that's overclocking.

 

The LGA 1366 i7s had a BCLK of 133MHz.

My LGA 1155 i7 has a BCLK of 100Mhz which can't really be changed at all.

 

So it varies from generation to generation, and chip to chip. Different CPUs have different base clock, multipliers etc.

 

QPI and RAM frequency differs with each generation of chips too, and is usually a multiple of the BCLK. eg. 6.4GHz QPI = 48x133MHz.

 

I don't really understand if there is a question there though, could you elaborate on what you would like to know?

Edited by p0is0n

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The base clock is largely irrelevant, and can actually be changed in the BIOS. Both 3820 or 3930k for example have a 100mhz BCLK and use 36x and 32x multi respectively.. not including Turbo clocks. This can easily be increased to up to 125Mhz but that's overclocking.

 

The LGA 1366 i7s had a BCLK of 133MHz.

My LGA 1155 i7 has a BCLK of 100Mhz which can't really be changed at all.

 

So it varies from generation to generation, and chip to chip. Different CPUs have different base clock, multipliers etc.

 

QPI and RAM frequency differs with each generation of chips too, and is usually a multiple of the BCLK. eg. 6.4GHz QPI = 48x133MHz.

 

I don't really understand if there is a question there though, could you elaborate on what you would like to know?

Yeah cheers mate I thought as much. I am looking at buying a SandyBridge-E (i7 3930k) so the BCLK would be 100Mhz as opposed to my current i7 960 at 133Mhz. I wont be overclocking, never do, but I do want synchronous RAM in relation to the BCLK/QPI that's all.

 

Cheers

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The base clock is largely irrelevant, and can actually be changed in the BIOS. Both 3820 or 3930k for example have a 100mhz BCLK and use 36x and 32x multi respectively.. not including Turbo clocks. This can easily be increased to up to 125Mhz but that's overclocking.

 

The LGA 1366 i7s had a BCLK of 133MHz.

My LGA 1155 i7 has a BCLK of 100Mhz which can't really be changed at all.

 

So it varies from generation to generation, and chip to chip. Different CPUs have different base clock, multipliers etc.

 

QPI and RAM frequency differs with each generation of chips too, and is usually a multiple of the BCLK. eg. 6.4GHz QPI = 48x133MHz.

 

I don't really understand if there is a question there though, could you elaborate on what you would like to know?

Yeah cheers mate I thought as much. I am looking at buying a SandyBridge-E (i7 3930k) so the BCLK would be 100Mhz as opposed to my current i7 960 at 133Mhz. I wont be overclocking, never do, but I do want synchronous RAM in relation to the BCLK/QPI that's all.

 

Cheers

 

To elaborate on this a little.. RAM Speed is just a multiple of the base clock, so 1600MHz = 16x100, 2133MHz = 21.33x100 & 2400MHz = 24x100 for example. Most RAM is just rated to a certain speed eg. up to 1600MHz so this will work at 1600MHz regardless of which platform/cpu etc. you're using.

 

Hope that makes sense.

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But the RAM, being DDR means it would be 8 x 100, not 16 x 100, right?

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To elaborate on this a little.. RAM Speed is just a multiple of the base clock, so 1600MHz = 16x100, 2133MHz = 21.33x100 & 2400MHz = 24x100 for example. Most RAM is just rated to a certain speed eg. up to 1600MHz so this will work at 1600MHz regardless of which platform/cpu etc. you're using.

 

Hope that makes sense.

 

Yep, I'm not a layman, I've built my own PC's for over 8 years. I only just recently built (18 and 12 months ago respectively) the 2 PC's in my signature, after 4 years with a Core2Duo setup. Quite obviously Intel had a FSB quad pumped and it was beneficial to match the RAM frequency with the frequency of the Front Side Bus, Synchronous in effect a whole number multiple (1:1 ratio), lest the clock cycles be out of phase and not 100% efficient - asynchronous.

 

All I was really confirming was that the newish BCLK frequency, as I knew it was directly linked to QPI and RAM as the previous FSB was linked to RAM etc.

 

I was just confused as I have been out of the loop, and merely seen "Core i7" being used with 100 and 133Mhz BCLK. I want my RAM as a synchronous whole number multiple for maximum efficiency (1:1 ratio). i.e. 1600Mhz with a 100Mhz BCLK has a multiple of 16, I don't want my system asynchronous, as I don't overclock, and want it as efficient as possible performance wise

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Guest xyzzy frobozz

Just my two bob's worth here.

 

With Sandy Bridge-E (LGA 2011), there are "strap" settings, which basically act as your BCLK. While it is possible to set the BCLK independently of the strap settings, in reality, you really only get stability to within +/- 2 to 5MHz.

 

So, for example, if you set the strap to 125MHz, you'd be pushing the limits of stability if you then set BCLK to 133MHz. The

 

Strap settings are generally 100/125/133/166MHz, with most chips being unstable beyond 125, and very few sable to get to 133MHz without very low multipliers.

 

Hope that helps. Like you I'm a layman, so there's probably a lot of others here who will be able to expand on this.

 

EDIT:- Just to clarify on how this relates to the OP - As you increase strap, RAM frequency increases at the same rate - i.e. 1:1.

Edited by xyzzy frobozz

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