Sandy Bridge-E OC Guide
Here is the PDF Version
SBEOC Guide PDF
Overclocking is an art, a science, and a way of life. For those of you who have been overclocking everything since you first learned how, to those of you who just are getting into it, overclocking can give you grief while at the same time giving you satisfaction. Today I am putting forward a work in which users of all experience levels can take something away from. So first we start out with Sandy Bridge-E, what makes it different from Sandy Bridge, and how that difference will affect our overclocking. Then we will venture into a theory of overclocking, and how frequency, voltage, and current are all inter-related and how they will affect your overclock. I will spell out how to overclock your SBe CPU. I will answer questions on memory bandwidth vs timings and whether high memory frequency will really impact normal daily computer usage, but at a basic level. I will give a walk-through of UEFI BIOS, especially catered towards GIGABYTE boards, but theory's which can be applied to many other boards. So I will cover basics that apply to all LGA2011 boards, then I will drill into the GIGABYTE board used for this OC guide. You can use this guide for any board and SBe CPU. Please be advised that locked CPU's will only be able to use their turbo multipliers and BLCK Straps to OC, and thus might not have the full CPU multiplier range above 39X-41X. I like to approach overclocking in a scientific way, so if some part needs to be clarified and its importance pointed out, please feel free to say so. If you have any questions please contact me through PM or post in this thread and I will provide individual support to anyone who asks for it.
The Guide will be split accordingly, if you must skip you may:
- Sandy Bridge-E Basics (Intel Specs, Voltage Description, PLL OV, SVID, What you need)
- How much power does SBe Pull? (CPU Power Consumption Measured and Analyzed)
- Overclocking Sandy Bridge-E, CPU Overclock Section (Steps to OC CPU walkthrough, Setting Voltage, Testing Stability, My Results)
- BLCK Straps Section (Do straps provide increased performance?, Their purpose, Walkthrough, Tips, My Results)
- Memory OC Section (Bandwidth Scaling, Timings Scaling, Walkthrough, My Results)
- Digital PWM Power Settings (UEFI setting explanation/walkthrough, applies to many boards with Digital PWMs)
- Extra OC Tips and Resources
Overclocking will reduce the lifespan of your CPU, it will void the warranty of your CPU and your Motherboard and most likely that of your memory too. It is harmful to components, and death of said components may occur. Higher voltages and temperatures can cause this death more readily. Of course nothing might die at all, but it is a risk every overclocker takes. If the risk is worth the reward to you then proceed. I take no responsibility if you break, harm, kill, or void your warranty by doing anything I say here on in. I have tested everything I talk about and recommend with great results, please be advised that your results may differ. I do not represent any company, and thus my word is my own and not a reflection upon any company of which I use their products or mention in this guide.
Sandy Bridge-E Basics
So let's begin with Sandy Bridge-E (SBe) and how it differs from Sandy Bridge(SB). First off the current SBe CPUs, the 3960X and 3930K, are both 6-core chips meaning that you have 2 extra cores. These 2 extra cores introduce some challenge as 2 more cores is 2 more cores that have to reach the same speeds. As your OC is limited by the maximum speed of the worst core, introducing 2 more cores doesn't help those probabilities. Next you have the issue of heat, there is a lot more heat with SBe, not only because of the 2 extra cores, but also because of the System Agent and QPI/VTT which both have increase maximum current ratings compared to SB. Here is a chart that I made using the Intel datasheets, I made them to help consolidate info:
Look at those high current ratings, those are all inside the CPU, and thus all contribute heat. You can even add them together for total values. When the 4-core SBe CPU's come out notice that their System Agent and VTT are basically the same.
We also have a change in the maximum voltage's from SB to SBe. MOST IMPORTANTLY Vcore has be reduced to 1.4v as VAbsolute. This shouldn't be taken lightly, but it might also be no surprise that SBe requires more voltage than SB for the same frequency.
Now there are a few other things that have changed, first off CPU PLL can be taken to 2v, but I wouldn't go over 1.95v. QPI/VTT(VTTD/A) and System Agent(IMC/VCCSA) can both be increased to 1.4v. This is much more than SB. I tossed up the load line slope in there, not for any other reason than to establish that the rating for the VCCLL is a slope, which is also a mOHM rating. Now remember back in high-school when you took geometry/Algebra? A lot closer to 1 is a vertical nice and a Slope closer to 0 is a horizontal line. Think of that line as the drop in voltage under load, so 0 slop would be no drop, and 1 would be all drop. This is only important for GIGABYTE boards as the slope is given as percent rating, so users can understand the meaning behind the percent.
So I made this chart, to explain the voltages as well as what they correspond with. I like to know what I am pumping voltage through, I am sure some of you would like to know too. Now those maximum rating are subjective, many will pump more or less into their CPU depending on how they feel and how long they want their CPU to last. I will give my suggested voltage ranges in a little bit. VTTD provides voltage to the PECI, the PECI is the part of the CPU that connects the cores and chipset to external logic devices that need readouts like temperature. It contains the DTS(digital thermal sensor) which are implemented as analog to digital converters and calibrated at the factory. Unlike with SB where the System Agent voltage was useless to a point, with SBe it is all but very important for memory OC. GIGABYTE went as far as to call it the IMC (Internal Memory Controller) Voltage. We still have QPI/VTT and it is important still as well. So now with SBe both System Agent and VTT need to be raised for memory OC.
CPU PLL Voltage Override (Overvoltage): What the Heck does it do?
So I asked that question to an Intel Overclocking Engineer his explanation was roughly: We went through the BIOS settings trying to find setting that if changed could help overclock our CPUs further. We came across this setting. Think of the CPU PLL voltage as a voltage that is provided to the CPU, but then "clipped" down to an approximate voltage. No matter what that input is whether 1.3v or 1.9v it is clipped (hypothetically let's say 800mv after clipping (he didn't say how much)) that way other devices can use the PLL voltage and clip to what they need. The CPU PLL Overvoltage allows for less clipping of that voltage. It can also reduce the lifespan of the CPU, but nothing noticeable.
So those of you who think that increasing your PLL voltage will help with that setting, it really doesn't. But with SBe I have found that increased CPU PLL can help stabilize higher frequency overclocks. That wasn't the case with SB.
What is SVID and how does it affect Overclocking?
SVID is a 3-wire digital communication protocol between the CPU and the PWM, it allows for the CPU to change its VID on the fly to fit the frequency selected. That is why you can increase the base frequency +/- 6-7 multipliers and the CPU remains stable, because SVID is increasing the VID without you knowing. Now this doesn't stop unless you manually set the voltage, so when users use DVID offset, they should be aware that their stock VID really isn't constant. That is why I do not recommend DVID with SB or SBe, at least not above 1.4v. SVID potentially can increase voltage to 1.52v on its own, but that has never really been seen. SB and SBe both have this 1.52v max for SVID. Now with SBe we also have the System Agent voltage, VCCSA or the IMC (internal memory controller) voltage, and this voltage now has SVID! Although I haven't seen much automatic change to this voltage, it can happen.
Now that we have covered some basics let's move to required hardware.
So what do you need to OC?
Any "K" Series or X series Processor will have unlocked multiplier, which is pretty important. With SBe we will see a 4-core CPU, that has a locked multiplier. So with that CPU the BLCK dividers can be used, which can also provide a decent overclock. I used a 3960X
You need an X79 chipset board with a LGA2011 socket. It is nice to have a board with voltage read points, but it isn't really required at all for 24/7 users. It is also nice to have POST code Port 80H POST code read out display, but you can also buy one. The VRM is important with SBe, as is overall spacing. I am not going to go into it, but I used an X79-UD7
SBe can clock trashy memory like it was that $500 kit. More stick=harder to OC to higher frequency. Higher density is the same thing. 2400 MHz is the goal for many users, I used 2 pairs of cheap Corsair non-dominator 2000 MHz cas9 2T memory and I was able to hit 2400 MHz. Please be aware memory clock is VERY dependent on the CPU. Unlike SB where every CPU could do 2133mhz, with SBe not many can do 2400mhz. You CAN mix and match memory, you can even set their timings differently, and their voltage, but it is very much recommended to use the same memory. It is also recommended that you buy a quad channel kit rated for your target clock. G.Skill, Corsair, and Kingston have some kits. SBe can run dual channel with 2 sticks, triple channel with 3 sticks, and quad channel with 4 sticks. I used two kits of Corsair I used CMX4GX3M2B2000C9
Water-cooling or top-notch air cooling is recommended for any OC over 4.5ghz with SBe. Please take note that many coolers used on socket LGA1366 can fit on LGA2011 with adjustment. SBe socket has holes at the same dimensions and placement as LGA1366, but instead of being thru-hole it instead has screw holes built into the socket. Anyways I was able to get my Antec Kuhler 920 to work, and it was because of two reasons. First of all the screw holes on the socket are a bit bigger than standard size, but they are a standardized size. They also don't bottom out, they are open ended so if you have a screw thinner than the hole you can thread it through. Next you can go to Home Depot (hardware store) and buy some screws that fit the new socket, which is what I did. Also for reference, the Coolermaster Hyper 212+ fits the new socket's screw holes perfectly. I used the Anteck Kuhler 920
This is important with SBe unlike with SB. SBe is a power hog, they said Bulldozer was a power hog, well they must not have foreseen Intel doing the same thing. SBe can pull 350-400 Watts at 4800mhz+ before power conversion of the VRM. That is a lot of watts. I used Corsair AX1200
Those are the only parts very important to OCing. Personally I bought a few optional parts:
A digital voltage meter, it has two probes, read and black and they can measure voltage. You can pick one up at any electronics store like Home Depot, even stores like microcenter carry them. They can be had for as little at $5-10 USD for cheap ones, and upwards of $100-200 for very nice ones. Really even a cheap one is better than software. Analog meters are cheaper, but they just have a needle that points to a voltage, don't buy one of these. Buy one with an LCD screen. Many boards have voltage read points, and these points are made to be used with a Digital Multi-Meter (DMM from here on out). Not only can you read your VCore in real time, as well as other motherboard voltages, but you can also test out your PSU and see how well it's voltage regulation is. A DMM is 10x better than any PSU tester, and cheaper usually too.
I bought some from my local Microcenter, pretty cheap, I put them on un-heatsinked components, like the MOSFETs around the board. You really don't need to put heatsinks on them, but I thought it looked cool. Plus aftermarket copper heatsinks always work better than stock ones.
Fan for the board:
If you are using watercooling then you are disregarding the airflow required around the CPU socket, particularly for the memory and VRM. With SB heat wasn't really the enemy, but with SBe it is the #1 enemy. A fan over the VRM heatsink is recommended for all LGA2011 boards. You will even see Alienware computers come with directional fan over the VRM with LGA2011 boards.
You can go to Radio Shack, Home Depot, or Microcenter and buy a $30 wall power meter; it will tell you power consumption at the wall in watts. Reviewer's use these. You can also buy a DC power meter, Zalman just released one, and it has decent abilities, up to 250W of the 12v rail of your PSU on the 8-pin connector. This is as close as one can get to telling CPU power consumption, without worrying that too many other components are using the same rail. The CPU has its own connector to help reduce the noise and EMI between components, we a user can take advantage and get a nice power reading.
A $3 wrist band can save you hundreds of dollars in dead hardware, and hours of frustration. There is no shame in being safe.
There are some really fancy Fluke IR thermometers and then there are some cheap ($15) laser ones with limited temperature ranges. You can buy one from an auto-parts store or Microcenter carries cheap ones in variety. It is nice to be able to read temperatures without a probe, and most work just fine. The more expensive ones can capture a thermal IR image, and they are very nice.
These are sometimes included with tech benches, but now some computer hardware stores sell them separately, Microcenter carries them in a pack. They can replace your case's buttons and make it easier for you to power, restart, and clear CMOS on your board. Of course if your board already has built in buttons, like my UD7 does, then you don't really need these.