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  1. #1
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Overclocking the Pentium G3258 – The Basics

    Overclocking the Pentium G3258 – The Basics


    Two cores, low power consumption, good overclocked performance in single threaded applications – what’s not to like about the Pentium G3258? It’s a fantastic processor in its own right, however, when we take price into consideration, it becomes a no-brainer purchase for a HTPC or casual gaming. The overclockability of these CPUs also makes them fun to experiment with. That brings us to the purpose of today’s musings, a guide on how to overclock the G3258.


    The basic principles of overclocking these CPUs are similar to Haswell – at least from a perspective of which voltages to adjust. The main difference being the lower physical core count and lack of hyper threading. While this has an impact on threaded application performance (naturally), it does equate to lower operating temperatures and very low power consumption. Unlike their Haswell brethren, if one is using good forms of cooling, it is possible to run out of voltage headroom before running into thermal limitations.





    Expectations/Requirements Rundown
    • Conservative overclocks of 4.5GHz are achievable on good CPU samples with 1.30Vcore or less with air-cooling. Fully stable frequencies in the region of 4.8GHz are possible with water cooling (closed loop water cooling such as the Corsair H100i). Most of our samples are capable of 4.8GHz with 1.42~1.46Vcore.



    • Long term effects (such as degradation) of running voltages over 1.40V into these CPUs is not yet known.

    • We recommend using a good air cooler or closed loop water cooler to overclock these CPUs. Ideally full load temperatures should be kept under 80C (core DTS). Higher temperatures may induce stability.

    • We use Realbench stress test to evaluate our CPUs for stability. The stress test in Realbench is more difficult to pass than other third party tests such as AIDA. As a result, you may notice higher processor frequencies are possible in other tests. We use Realbench because it is a worst case scenario load and features real-world applications such as Handbrake concurrently with Luxmark while stressing memory to evaluate processor stability. Doing so allows us to gauge frequency expectations more realistically than “lighter load” stress tests.

    • Power consumption is low. At 4.8GHz power consumption is around 88 Watts under Realbench stress test loads with 32GB of memory at DDR3-2133. Load temperatures at these frequencies are below 80C (DTS) on a good water-cooling setup with 20C ambient temps.

    • Memory frequencies above DDR3-2133 with 16GB or 32GB of memory can be difficult for some CPUs. VCCSA, VCCIO-D, VCCIO-A and cache voltage can help improve stability for memory. We do not recommend using more than 1.30V for any of these rails long term. In most cases 1.15V should suffice for memory frequencies up to DDR3-2133 and default cache speeds.

    • For sake of stability and easier setup, memory kits rated for Z87/Z97 are best choice. If plug-and-play operation is desired, sticking closer to DDR3-1600 is wise. Higher speeds may require manual tuning (even with XMP) – as each processor sample is different and there is no magic bullet setting for all samples to ensure stability past stock specifications.

    • Do not combine multiple memory kits even if from the same model. Use a single memory kit rated at the desired frequency and density.

  2. #2
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Quick Setup
    • Download and install the latest EFI for your motherboard before proceeding with any overclocking.

    • Back up the operating system by using the built-in back up features of Windows or use a third party tool if preferred. This will create an image to fall back on in case the installation becomes corrupt due to instability when overclocking.

    • Install and run Realbench’s stress test for 2 hours with the correct amount of memory assigned for your system. Doing so ensures the system is at least stable at stock operating parameters. Do not continue to the overclocking section of this guide until basic stability has been evaluated.

    • If the system is stable at stock then proceed to the overclocking tutorial below. If not, navigate to the troubleshooting section.






    Enter UEFI by pressing delete during POST and navigate to the AI Tweaker section:




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    Set AI Overclock Tuner to manual or XMP (XMP if your memory has XMP programmed).



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    Set the core ratio to 43X to start off with. If XMP has been selected, there is no need to do anything further. You may save and exit UEFI by pressing F10 and confirming.





    If setting DRAM speed manually, set the frequency the memory modules are rated at by changing DRAM frequency to the same value:


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    At this point wer can save and exit UEFI and proceed to the operating system. Assuming all is well, the OS will load. Open a temperature reporting tool, (Core Temp, AIDA or Real Temp), before running Realbench to monitor temps. Start Realbench and keep an eye on temperatures for the first 10~15 minutes, if they are over 80C with this kind of overclock, you need better cooling. If not, let the stability test run its course.

    Assuming the test passes you may continue to use the system, tune voltages or overclock further, (if there is sufficient temperature margin remaining for the cooling solution used). To over clock further, enter UEFI once again, increase the core ratio by +1 and repeat the stress testing process.




    If the stability test fails, or the system crashes, then some manual changes will need to be made in UEFI.

  3. #3
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Troubleshooting Overclocked Instability


    If ROG Realbench causes the system to crash (BSOD), reset, or gives an error when overclocked, it could be due to a number of factors. If the system is perfectly stable at stock, then overclocked stability is usually down to one of these:
    • CPU instability – not enough voltage or CPU frequency too high.

    • Memory Instability – memory overclocked too far, or CPU memory controller not capable of sustaining the memory clock being applied.








    CPU Instability


    If the CPU is unstable when overclocked using auto settings for Vcore, then manual changes may be necessary. A hint towards CPU related instability comes from looking at BSOD codes. If the BSOD gives a message related to clock interrupts this is very often Vcore or processor frequency related. Depending upon how much voltage is being used and the frequency the processor is being run at, there may be some room to increase Vcore to see if it helps improve stability. Of course one needs to be mindful of temps and how much voltage is being applied.


    Open CPU-Z and run the Realbench stress test. Note the voltage being applied under full load; CPU-Z displays Vcore. Enter UEFI and increase the voltage by adding 0.05V to it. As an example, if we see 1.30V in CPU-Z when the processor is under full load, we would add 0.05V to that value in UEFI to give us 1.35V. Be careful not to mix up values here, do not confuse 0.05V with 0.5V. Increasing Vcore by 0.5V would be catastrophic for the CPU!


    We are basing the adjustments in this guide on the usage of “Manual” Vcore not “Offset” or “Adaptive” modes. The latter two are more complicated to use for newcomers and can be dealt with after one gains some experience of the platform.


    Manual mode is set by doing the following in UEFI:


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    We can save and exit UEFI and now run the stress test again. Again, keep an eye on temps under load. If everything is within desired operating range we can leave the system to complete the stress test. If it passes as a result of an increase of Vcore, great, we can move on and see how the system holds up to regular use for a few days.

    If it does not pass, then we need to make a choice at this point. We can accept a lower overclock. Rule of thumb is not to increase Vcore more than 0.05V to go from one multiplier ratio to the next. Sticking to this rule ensures that we do not increase current through the processor substantially for little performance return. Let’s say our CPU is perfectly stable at 4.6GHz with 1.35V, and we attempt 4.7GHz, which is not stable even with 1.40V applied. In such a scenario, it makes sense to settle at 4.6GHz at 1.35V, instead of increasing voltage past 1.40V for 4.7GHz.


    Some boards have a fully manual mode option - which allows all other voltages to be set directly without using offset/adaptive:


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    Setting this to enabled makes setting the voltages easier - offset and cache voltage is harder to predict without and one has to rely on monitoring and guesswork. Recommend enabling this option to start off with if your board has it. Do be sure to enter all the associated voltages manually (guidelines are given below for start points).


    Cache voltage can also help, though I’d advise more caution with increasing that as much as Vcore. General advice is to stay below 1.30V.


    My musings on running conservative voltages are geared to help you obtain an overclock that does not result in degradation of the processor in a short time. Given the cost of these Pentium CPUs however, it is attractive to do away with such rules and be gung-ho about voltages and degradation. If pushing the CPU as hard as possible appeals to you, then by all means do so. I’ve been doing the same here.



    It’s also possible that both the memory and processor are unstable, which can be more difficult to debug (more on memory instability below). Usually, it’s a good idea to lower either the CPU speed or memory speed and see how that affects the instability. Lower CPU speed first and check if the system still crashes. If it does, lower the memory frequency too and check if that has any impact. By doing so, one can work out where the instability is coming from and work on getting the system stable.














    Memory Instability


    BSODs with codes of “Page fault in non-paged area” or “PFN list corrupt” are an indication of memory instability. A system may also lock-up or reset if the memory instability is severe. If the system is locking up, then running a memory only stress test such as Memtest or HCI Memtest (the latter is a pay for version which I personally use) can help pinpoint the cause and debug it.


    There are several voltages associated with memory on the Haswell/Pentium architecture:


    VCCIO-D

    VCCIO-A

    VCCSA

    DRAM Voltage

    And to a lesser extent cache voltage.



    • Most of the time, the auto parameters for these voltages will scale the voltages as DRAM frequency is increased. Unfortunately, some CPU require more or less voltage than the auto rules apply so manual adjustments may be necessary. I’d advise to use smaller steps in making changes upwards or downwards from the auto value - steps of 0.02V.

    • Conservative advice is to stay below 1.20V for VCCIO-D, VCCIO-A and VCCSA. Cache voltage below 1.30V.

    • Recommendations for a manual start point for VCCIO-D, VCCIO-A and VCCSA is 1.10V if running memory speeds higher than DDR3-1866. If running memory speeds of DDR-2133 or higher, start with 1.15V. Work up or down from there.

    • There is some additional info on why voltages such as VCCIO-D, VCCIO-A, VCCSA and DRAM voltage need to be reduced instead of increased in certain situations. Granted, “beginners”, should not encounter such things, however, it does not hurt to improve our understanding. CLICK HERE
    • DRAM voltage should not be adjusted if using XMP, as the profile will automatically apply the specified voltage. If using kits with no XMP (an unlikely scenario), then manual changes to ensure the specified level of DRAM voltage for the memory kit is applied.

    This should be enough to get started. More to come!

  4. #4
    ROG Guru: Grand Master Array HiVizMan's Avatar
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    Cheers for this Raja - I am going to get a couple of these just to play with. Great to teach my girls how to OC on.
    To help us help you - please provide as much information about your system and the problem as possible.

  5. #5
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    I know some folks are buying 5 at a time. Gary found one in his five that does passes stress testing for an hour at 5G so far..

  6. #6
    ROG Guru: Grand Master Array HiVizMan's Avatar
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    At the price these babies are going for I can understand that. One in five is a pretty good odds for finding a reasonable CPU - most of the other model CPUs I have binned have been more like 1 in 50. (3770K and 4770K) LOL
    Last edited by HiVizMan; 07-08-2014 at 03:48 PM.
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  7. #7
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Whats the average freq you are seeing?

  8. #8
    ROG Guru: Grand Master Array HiVizMan's Avatar
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    I do not have a particularly great air clocker. Needs 1.4 volts for 4600MHz.
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  9. #9
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    That is about 100MHz below the norm.

  10. #10
    ROG Guru: Grand Master Array HiVizMan's Avatar
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    Don't I just know it, but I have two more arriving on Thursday so I do expect better - fingers crossed.
    To help us help you - please provide as much information about your system and the problem as possible.

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