I have seen a few posts here and there where people try to push the bclk up past 210 or so and run into some problems. I wanted to post a guide consisting of a strategy that has worked well for me for finding the max
stable bclk and then in turn using that to eventually reach the desired core and memory frequencies.
For reference, bclk is equivalent to base clock or CPU Host Frequency in BIOS and the default is 133.
To start with, I lower the CPU core multiplier to 17x in BIOS. I choose 17x because the odd-value multipliers tend to let me lower the Vcore a bit compared to even-value multipliers (18x and 20x). The reason to lower the CPU multiplier is so that we are not overclocking the cores as much along with everything else at once. Chances are if the chip is set to 21x and you try to push a bclk of 210 or greater that there will be some kind of issue that will come up and at that point it will be difficult to determine where the problem is. Since some chips need considerable Vcore even at lower frequencies, I would suggest starting at an even lower multiplier such as 15x. If you know you have a chip that can handle low Vcore at higher frequencies, then 17x should be fine. To start with, here are the configuration settings I would suggest:
Frequency Settings CPU Host Frequency: 160
CPU Multiplier: 15x
Uncore Multiplier: 16x (Minimum allowed)
Memory Multiplier: 2:6 (Equivalent to 6x and the minimum allowed)
QPI Frequency: 4.8 GT/s (Equivalent to 18x multiplier for the processor’s QPI link)
PCI-E Frequency: 101
Voltage Settings Vdroop control: With Vdroop
Vcore: 1.3v
VTT: +100mv for Classified boards and +200mv for E758 boards
DRAM Voltage: 1.65v
CPU PLL: 1.65v
QPI PLL: 1.2v
IOH PLL: Auto (Default 1.8v) *
IOH Vcore: 1.1v
IOH/ICH Voltage: 1.5v
ICH Voltage: 1.125v (To help prevent USB related issues at higher bclk)
NF200 Voltage: Auto **
CPU Impedance: Less *
QPI Compensation: Middle or Less (My system fails to post with less, but feel free to try what works best) *
PWM Frequency ( 800 KHz ) (Keep at minimum due to higher Vreg temps otherwise with upgraded Vreg cooling, this can be increased)
VTT PWM Frequency ( 610 KHz ) *
CPU PWM Frequency ( 1200 KHz ) *
* Classified E759/E760/E761/E762/E769
** Classified E759/E762 The two items we have to concentrate on when increasing the bclk at this stage is the Uncore frequency and QPI Link Frequency. Using the above configuration, we use the minimum 6x memory multiplier to start with so that we do not find ourselves limited by memory frequency and we use the lower CPU multiplier so we are not limited by core frequency. We set QPI Frequency to 4.8 GT/s even on
965/975 processors. This is because 4.8 GT/s is equivalent to 18x QPI Link multiplier, and we want to keep this frequency as low as possible to prevent freezing issues as we increase bclk. This frequency and the GT/s increases with bclk.
The VTT voltage is important at this stage, because VTT is the voltage for the processor’s Uncore, which includes the L3 Shared Cache, Integrated Memory Controller (IMC), and QPI. The base VTT voltage is 1.1v for the E758 and 1.2v for the Classified boards. It is for this reason that I suggest above to set a smaller increase over base with the Classified boards because it has the higher default VTT. I do not know the base voltage for the Micro/LE boards, but the intended target voltage to start with is 1.3v.
Stage 1 (Base clock): Now we can start working on the bclk. I would suggest first starting at a bclk of 160, which is generally not an issue for the i7 processors. My advice is to use the E-Leet utility once everything is set in BIOS as shown above. For stress testing, we will want to use LinX 0.6.2 because of how quickly it can stress the system. For a 6GB system, I normally allocate 3GB of memory to LinX and run 10-passes while working on bclk. Make sure you have Real Temp running so you can keep the temps in check. Core temps should stay below 85C.
We start at bclk 160 and run LinX. If all is well, I would suggest the following increment scheme:
160-180: 10 notches up for each test
180-200: 5 notches up for each test
200-210: 3 notches up for each test
210-215: 2 notches up for each test
215+: 1 notch up for each test
The higher we move up in bclk, the more difficult it will be to maintain stability, which is why I suggest smaller increments for higher bclk.
As you increase bclk, there will likely come a point where you get a BSOD, either code 0x124 or 0x9c depending on OS. When you get this code, it is time to bump up the VTT. I would suggest an increase of one notch at a time, or +25mv until stable. With a good chip that has a strong IMC, you will likely be able to get to bclk 210 without too much trauma. At some point, you may reach a wall where after running LinX for a bit, the system will freeze and you may even have to power down the system manually in order to get things back up and running again. At this point, you know you are getting close to the limit for the bclk while still being stable enough to run LinX. If this happens, my suggestion is to try to increase the IOH voltage a bit. An increase of 1.1 to 1.2v allowed me to gain an extra 2-bclk over what was previously stable.
In addition, some people have had success by increasing the PCI-E frequency. The max I would suggest for this is 104-105. Any higher and you may run into issues with your onboard network ports or other devices. My network ports failed at PCI-E 110. You may also try increasing the QPI PLL a bit further to say 1.3v. With my tests, anything above 1.2v was not effective, but your results may vary.
In my experiments, the IOH/ICH I/O and ICH Vcore voltage made no difference as far as maxing out bclk goes. However, I have noticed in the past that some various USB related issues would creep up at the higher bclk and a small increase in the ICH voltage would take care of this.
As an example, for my 920 chip, I found a bclk limit of 219. Any higher and the system would freeze while running LinX after a bit regardless of where I set the IOH Vcore / PCI-E frequency. I could get it up to 224 on air, but it was not stable and my goal was stability. This was done via the E758.
Stage 2 (Memory): Now that we have found maximum bclk, we can work on the memory next. Lets assume that we reached a bclk of 215 as our max. We can look at several calculations to see where things end up at with the different memory ratio choices:
Bclk: 215
Memory Frequency Ratio: 2:6
Uncore Multiplier: 16x
Memory Frequency: 215x6= 1290 MHz
Uncore Frequency: 215x16= 3440 MHz
Bclk: 215
Memory Frequency Ratio: 2:8
Uncore Multiplier: 16x
Memory Frequency: 215x8= 1720 MHz
Uncore Frequency: 215x16= 3440 MHz
Bclk: 215
Memory Frequency Ratio: 2:10
Uncore Multiplier: 20x
Memory Frequency: 215x10= 2150 MHz
Uncore Frequency: 215x20= 4300 MHz
For most of us, we will want to stick with 2:8 maximum, because otherwise we are pushing the memory and Uncore quite far. Now lets say we choose 2:8 but have a 1600 MHz memory kit. With the above configuration, we are overclocking our memory. At this point, we have two choices, to stay at 2:6 for the memory frequency, or we can try and loosen the timings some. For example, for an 8-8-8-24 kit, try 9-9-9-24. If you decided to overclock the memory, I would highly suggest running Memtest86+ to confirm memory stability before booting the OS.
Stage 3 (CPU Cores): Now with the bclk, memory, Uncore, and QPI Link out of the way, that leaves over the CPU core frequency. At this point, you can decide where you would like to have your core frequency at by using the appropriate multiplier. Assuming again, that our max was bclk 215, here is what we would get using a 19x multiplier.
215x19= 4085 MHz
At this point, the primary thing you have to concentrate on is Vcore. You will likely have to increase that some to reach stability since the core frequency is now much greater than it was before. If you have previously overclocked the same chip, then you will have some frame of reference as to where the Vcore needs to be at for a specific core frequency.
As always, make sure to keep your core and Vreg temps in check. When you reach your goals, you will want to run the appropriate long-term stress testing using Prime95 Blend / LinX like you normally would to determine if the system is completely stable.
Conclusion: This guide is primarily for those that want to find out the limits of their chips and like to push things to the limit. This guide can also be used if you want to break things down into several pieces so that you are not overclocking all the different components at once or if you simply want to see how much VTT it is going to take to run at your desired bclk so that you can use that VTT as a point of reference later on.
Notes: I have run into one case where a new BIOS version limited my bclk. Reverting back to an older version fixed that. If you run into a wall sooner than anticipated then this might be something to keep in mind.
<message edited by linuxrouter on Tuesday, November 17, 2009 1:42 PM>