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    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Apr 2011

    Ivy Bridge-E Easy Overclocking Guide – The Listy/Wordy Edition

    Standard disclaimer: Overclocking is not guaranteed to work, or guaranteed to be reliable. Do so at your own risk.

    Read the guide through in its entirety before attempting any overclocking!

    Ivy Bridge-E CPU Core Overclocking Overview

    1) In my binning of 45 samples, 2% of CPUs will do 4.8GHz at 1.40V. 20% will do 4.7GHz. Almost 48% will do 4.6GHz at 1.40V. 28% will do 4.5GHz at 1.40V. 2% will do only 4.4GHz at 1.40V. The average frequency is therefore 4.6GHz on a reasonable CPU sample. Not a massive sample size, but I think it gives us a realistic indication of what to expect from retail processors.

    2) The power draw of Ivy-E is very low. We measured 120 Watts at full AVX load at 4.6GHz. However, we’re dealing with a smaller substrate/process node which means getting heat away from the die quickly is key. Same trend we are used to by now on the 22nm process.

    4.6GHz at 1.40V is doable using water cooling – we get loaded temps of around 80C on a good triple radiator water loop. For users with air coolers, we recommend a maximum of 1.30V for Vcore - of course this is dependent on the type of air cooler and its capabilities. Use a voltage that keeps loaded temps below 75 Celsius or so.

    We do recommend placing a fan over the VRM heatsink if the system is going to be overclocked.

    Overclocking Ivy-E for the masses is centered on two voltages: Vcore and VCCSA (more on VCCSA later).

    (i) For Vcore the highest we’re using here internally is 1.40V (cooling dependent obviously).

    (ii) Our auto rules will set Vcore and VSSA as changes are made. We recommend starting on auto and simply setting the multipliers, then tuning voltages lower or higher depending upon the CPU sample.

    That’s most of the basics in short-form apart from specifics about Ivy-E and memory overclocking. Before we get to the overclocking section, there’s a memory kit related topic that comes up on these forums (and others) frequently. It seems many users are not aware that combining memory kits – even those of the same model can lead to system instability. Make sure you read the section below before proceeding to overclock the system.

    Notes on X79 memory purchasing

    Let’s start with what not to do: DO NOT COMBINE MULTIPLE MEMORY KITS, EVEN IF THEY ARE THE SAME MODEL. While it may seem attractive to populate as many memory slots as we can, there is a sensible way of doing it that makes setting the system up and getting it stable easier. Purchase a single kit rated at the desired density and timings you wish to run – we recommend memory kits rated no faster than DDR3-1600 for ease-of-use. Speeds faster than DDR3-1600 require an IMC that is “strong”, and may require lots of manual tuning to obtain stability.

    Quick check list of Ivy-E memory related items:

    1) DDR3-1866 is supported as a stock speed. However, it is only supported with one DIMM per channel. If all slots are populated, then the maximum supported memory speed is DDR3-1600. Both situations are likely subject to memory timing, too. Intel usually makes this information available in their white papers.

    Supported speeds are those the processor can run without needing any kind of voltage adjustment. Anything faster than this is defined as overclocking and quite obviously, may require adjustment of voltages and memory timings to work.

    The idea then is to select a memory kit that suits one’s mindset. If plug-and-play operation is desirable, then it would be wise to select memory kits rated no faster than DDR3-1600 or DDR3-1866 (depending upon density).

    If one is inclined to tune a system manually, then purchasing a faster memory kit is possible. Bear in mind that performance gains from running faster memory are minuscule in most applications. If budget is constrained, or you’re simply looking for good performance return for expenditure, then spending excessively on fast memory kits is ill-advised.

    2) Look for memory kits that are qualified to run on the platform they will be used in. In this case, we are looking for X79 qualified memory kits. Memory kits qualified on other platforms may not reach their specified timings when used on X79 and vice versa, too. That’s because the SPD and XMP is programmed with memory timings for the platform they were binned on.

    3) We’ll say it one more time: Don’t combine multiple kits to make up a higher density. Purchase a single memory kit rated at the speed and required density (other purchasing advice withstanding).

    Following the advice above should keep most out of trouble. If inclined towards memory related tomfoolery (overclocking or tweaking) then the following section is worth a read.

    Notes about Ivy-E's Memory Controller

    It’s time to start writing about about Ivy-E’s memory controller. On average, Ivy-E is a little more robust than Sandybridge-E when it comes to memory overclocking. Higher memory ratios are available (over DDR3-2400) and the CPUs seem to have an easier time reaching DDR3-2400.

    I like lists, they keep things on point without BS. My (naive?) belief is that people are more likely to follow lists than large paragraphs of text. Yep, it’s time for another list. This one’s about Ivy-E’s memory controller capabilities:

    1) Most Ivy-E CPU samples are capable of reaching DDR3-2400 with 32GB of memory.

    2) Some samples are capable of speeds beyond DDR3-2666 with 16GB of memory.

    3) As CPU core frequency is increased it can become more difficult to reach memory speeds over DDR3-2133. This situation is also affected by the amount of memory used. For example, it may be easier to run speeds over DDR3-2133 if only 16GB of memory is used.

    4) VCCSA is the voltage that helps facilitate memory overclocking on Ivy-E. DRAM voltage does too (obviously). Speeds over DDR3-2400 may require high levels of VCCSA if high density memory configurations are used. We have used up to 1.40V with 64GB of memory at speeds over DDR3-2400.

    5) Before you are wowed by the voltage or the promise of running DDR3-2400, remember that even if you find a single memory kit rated at these speeds, there is no guarantee that the CPU memory controller will manage the frequency. Each CPU sample varies - some are better and some are worse at overclocking.

    6) Bear in mind that memory timings are just as important as memory frequency. Chasing raw frequency at the expense of timings is worthless on a 24/7 system.

    Just because a CPU won’t run a given memory frequency in a stable manner, don’t despair! It’s usually "technically" faster to drop the memory ratio one step lower and run a tighter set of timings. Doing so can be complex, but that’s what the forum is for. We’re here to guide you on what to run in these situations. Ask!

    7) Memory speeds over DDR3-2400 may be more stable when using the 125 MHz BCLK strap.

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