Help Understanding BCLK straps on X79 Extreme 6

[kmo_9000]

I've looked elseware and haven't been able to find an answer. I have an X79 Extreme6 motherboard with an 3820 and I don't understand how the BCLK works.

As far as I have seen, there is no way to set BCLK straps manually. This is really annoying considering I was expecting being able to set them on an X79 motherboard.



In any case, according to the pic am I to understand that as long as I set the BCLK to below 113mhz it will strap to 100mhz?

If this is so then why does it still change the speeds of my ram? Any help with this would be appreciated as I'm finding this really confusing. It's not the same as most other x79 motherboards that just let you set the strap manually.

[Z O X]

Re: Help Understanding BCLK straps on X79 Extreme 6

Straps effect external clocks: SATA and PCIe.
RAM clocks are effected by IMC speed which in turn sits on same bus as CPU.

[kmo_9000]

Re: Help Understanding BCLK straps on X79 Extreme 6

Straps effect external clocks: SATA and PCIe.
RAM clocks are effected by IMC speed which in turn sits on same bus as CPU.

Ok then how do you set straps in the bios. There is no option to set straps, only to change the bclk.

If I set the BCLK in the bios it will effect the ram and cpu.

Let's say I set that BCLK to 125. What would the strap be and how would that effect my external devices?

It doesn't make sense to me, all the guides seem to reply on setting a strap manually to overclock. It's not clear to me how BCLK and straps are handled with this board.

[Z O X]

Re: Help Understanding BCLK straps on X79 Extreme 6

Setting clock to eg. 125 MHz sets strap to 133.
AFAIK, the CPU and IMC get 125 but system devices get 133(strap)-8(to get 125).
PCIe bus should work at 92 MHz, etc.

In other words, clock snaps to closest strap with CPU always getting selected speed,
but system devices nominal clock receives difference from closest strap.

Note that Extreme4 doesn't allow offset voltage with strap. Hope 6 is better ...

[kmo_9000]

Re: Help Understanding BCLK straps on X79 Extreme 6

Setting clock to eg. 125 MHz sets strap to 133.
AFAIK, the CPU and IMC get 125 but system devices get 133(strap)-8(to get 125).
PCIe bus should work at 92 MHz, etc.

In other words, clock snaps to closest strap with CPU always getting selected speed,
but system devices nominal clock receives difference from closest strap.

Note that Extreme4 doesn't allow offset voltage with strap. Hope 6 is better ...

Thanks for the explanation, I'll keep this in mind next time I try to overclock past 4.3ghz.

Not having manual bclk straps is pretty huge let down though. It seems like such a basic feature not to have.

[Z O X]

Re: Help Understanding BCLK straps on X79 Extreme 6

No, all the boards work the same, they just have different labels.
Straps are selected as they should be on Asrock boards, just mechanism is different ...
You didn't loose anything with xtr6 board. In fact, Asrock is/was only1 with working 166 strap ;-)

[parsec]

Re: Help Understanding BCLK straps on X79 Extreme 6

Wow, ASRock has really gone into left field with the BCLK on this X79 board.

The Intel intent and standard for the "straps" are 100MHz, 125MHz, 166MHz and 250MHz specifically, with no other settings. They are also only supposed to be applied to the CPU clock only, not any others such as memory.

It seems ASRock has ignored all this completely, so you are stuck with their poor explanation of the settings, as well as the potentially unwanted (and negative) side affects of their unique BCLK/CPU strap implementation. You'll need to experiment and hopefully get some insight from other users of this board. Good Luck!

[kmo_9000]

Re: Help Understanding BCLK straps on X79 Extreme 6

Wow, ASRock has really gone into left field with the BCLK on this X79 board.

The Intel intent and standard for the "straps" are 100MHz, 125MHz, 166MHz and 250MHz specifically, with no other settings. They are also only supposed to be applied to the CPU clock only, not any others such as memory.

It seems ASRock has ignored all this completely, so you are stuck with their poor explanation of the settings, as well as the potentially unwanted (and negative) side affects of their unique BCLK/CPU strap implementation. You'll need to experiment and hopefully get some insight from other users of this board. Good Luck!

I sent an email to AsRock support about this, I'm still waiting for a response.

But what I was expecting was to be able to set the gear ratio to something like 1.25 or 1.33 and be able to overclock the CPU without increasing the actual BCLK. As far as I know this is how every other motherboard has it set up.

So it seems to me like I can't set straps without adjusting the BCLK. And I'm still not sure if increasing the BCLK is safe on this motherboard.

[Z O X]

Re: Help Understanding BCLK straps on X79 Extreme 6

I sent an email to AsRock support about this, I'm still waiting for a response.

But what I was expecting was to be able to set the gear ratio to something like 1.25 or 1.33 and be able to overclock the CPU without increasing the actual BCLK. As far as I know this is how every other motherboard has it set up.

So it seems to me like I can't set straps without adjusting the BCLK. And I'm still not sure if increasing the BCLK is safe on this motherboard.

But you ARE increasing BCLK with different straps!
If you select eg. 1.25 strap (Asrock says 1.33 but all info I saw about SB-e lists 1.25, 1.66 an 2) the system receives 100 MHz clock while CPU receives 125.

Since DRAM speed is dependent on the bus CPU receives, it is also changing. This is happening on all boards.
Asrock allows about 12 MHz deviation from base clock. It is above stability limit for BCLK overclocking (without straps).
Straps allows one to reset bus speed as if CPU is running on 100 MHz bus.

Consider studying strap detail from SB-e overclocking guide ...

I guess you guys want something like 90MHz bus with 1.66 strap.
In Asrock terms that would be 156 MHz BCLK. The system will use strap 1.66 and subtract 10 MHz from base/system clock.