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Volt mod Guide: NVIDIA 8600GTS

Discussion in 'User submitted guides' started by _EffEcT_, May 1, 2008.

  1. _EffEcT_

    _EffEcT_ Regular member

    Nov 25, 2007
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    Voltage modifications, or as many people simply refer to them, volt mods, can either make you excited with anticipation of unlocked performance and crazy cooling or nervous at the thought of running out-of-spec and possibly dangerous voltages into your new, expensive and totally awesome piece of PC hardware.

    This article will cover the basics of voltage modifications. This will include the purpose, the after effect and the unique process of actually performing a voltage mod. Next these concepts will be implemented on an NVIDIA-based ASUS EN8600GTS Top Edition graphics card.

    The following acts of extreme computing, uber geek skills and general amazement will void your warranty. Other potential risks include failure of hardware and potential self harm. Only attempt the following if you feel the leet vibe and awesome skills to pull it off. Atomic and Haymarket Media take no responsibility for attempts that result in broken bits and injured people.

    When it comes to modifications of hardware, the enthusiast crowd ranges from your average user tweaking for personalisation through to your performance nut that wants to make piece of kit hit such a staggering level of performance that there is no care if it happens to die!

    Essentially, when it comes down to modifications there are soft-mod and hard-mods. Soft-mods are software based modifications of the hardware. This could be a Windows tweak, modified BIOS, a third party application that unlocks performance or any other means of software based changes.

    A hard-mod, on the other hand, is a hardware-based modification. This means physically changing, removing or adding pieces to the hardware to increase performance. The majority of performance enhancements that modify the voltage control on hardware are a hard-mod. There are exceptions to the rule, such as manually setting voltages through modified BIOS for 7800 series GPUs, these are however not only fairly irregular in existence (dependent on hard configuration) but also never quite as definitive as a hard-mod, be it soldering, penciling or penning, two points.

    Why volt mod?

    A volt mod is a hardware based modification, a hard-mod, and they commonly bridge two points and allow an effectively higher voltage through to the desired component. On a GPU, this desired component is generally either the core voltage (GPU vcore) or the memory voltage (GPU vmem). On a motherboard a volt mod may fix or lesson vdroop, increase vcore, increase vdimm or increase vMCH (chipset).

    The bridging of two points is commonly done in one of three methods. These methods include soldering voltage regulators between the two points and then tweaking to obtain a certain voltage, connecting two points with a conductive ink pen or connecting two points with a graphite trail from an everyday 2B pencil.

    The ability to use such a low-tech mechanism, such as a 2B pencil, to increase performance headroom is generally the key draw card for many individual’s move into hardware voltage modifications.

    As already touched upon, voltage modifications can allow for increased performance. This is predominantly the reason why most hardware volt mods are done. Additional reasons to perform a volt mod may include the need to improve a connection that is giving an otherwise underwhelming voltage supply.

    For example, a motherboard may state the CPU vcore as being set to 1.35v; however the digital multi-meter (DMM) reading states an actual voltage of 1.31v when the 1.35v setting is enforced via the BIOS. In this instance a volt mod could theoretically be incorporated so that the lack luster 1.31v actual reading will be increased to correctly relate to a 1.35v reading as per the BIOS set level.

    Volt mods are commonly incorporated by those seeking to break a certain performance barrier. For example, a volt modder may setup a volt mod so that the 1.35v setting within the BIOS reads a DMM stated actual voltage of 1.42v. This is commonly used to obtain a higher voltage input with the hope of a possible increase in stability at higher frequencies.

    Aside from the performance gains, there is the satisfaction of a job well done when a volt mod functions appropriately and gives the desired return.

    These two reasons are generally the core of why enthusiasts volt mod hardware.

    Tools of the trade

    For volt mods, from the easy to the extreme, this is a list of some of the tools and general gear you’ll need for the mods:

    25W soldering iron

    2B pencil

    Conductive ink pen

    Digital multi meter

    Variable resistors of differing resistances

    K-type temperature probe

    SMD grabber

    Roll of solder

    Spool of light duty black hook-up wire

    Spool of light duty red hook-up wire

    Hot glue gun

    Sea sponge


    Not all of these items are necessary, in fact, all are optional with the exception of the digital multi meter – it’s a must. The simplest of voltage modifications can be performed with just a 2B pencil and eraser; they can be as simple as that!

    If you’re looking to immerse yourself in the realm of voltage modifications, this is the list of goods you’ll undoubtedly need.

    The after effect of a volt mod can be numerous. The two most common of which include increased temperature, either from a voltage regulating IC or from the processing unit, for example a GPU, as well as increased potential performance due to the additional voltage giving stability to higher clock frequencies.

    The increased heat output is due to the increase in voltage flow through the IC and/or processing unit (PU). This increased voltage renders a higher waste heat output. Meaning it is important to have adequate cooling for the heat generating part.

    The cooling may take the form of additional heatsinks to otherwise bare chips or increased cooling performance, for example moving from air based cooling to water cooling. Inadequate cooling can result in a greatly reduced meantime before failure (MTBF) and product life span.

    The gains can be a substantial increase in performance and when taken to the edge, these gains can put the piece of hardware in a league completely of its own.

    Be sure to check the manufacturer’s warranty statements, but you can bet that 100% of hard-mods void any warranties. This is a process for the hardcore enthusiast elite who see warranties as being akin to toilet paper.

    NVIDIA ASUS EN8600GTS Top Edition

    As mentioned previously, volt mods can be done using a range of mediums and tools. For this particular guide we have the option to use the three main modification mediums, a conductive ink pen, graphite pencil and a soldering iron.

    The pens, pencils and soldering irons are readily available from your local JayCar, Dick Smiths Electronics or other electronics hobby stores.

    As stock, the NVIDIA 8600GTS has a GPU vcore of 1.35v and a memory voltage (vmem) of 2.1v. Through the use of hardware based voltage modifications, we’ll be increasing these voltages and looking to significantly increase the performance through overclocking of the 8600GTS.

    The steps to performing the necessary voltage modifications to the 8600GTS are clearly outlined below in an overview reference shot of the back of the card. Use this, in conjunction with the close up shots, as a reference point for conducting the volt mods. With that said, it's commonly believed that a photo is worth a thousand words. As such, from here on in we’ll be keeping it quick and concise with rather self explanatory images and a bit of info on the mod. Enjoy.

    Use this shot of the back of the NVIDIA ASUS EN8600GTS Top Edition graphics card as a reference for locating the necessary areas and parts for the voltage modifications:

    VGPU measure point and initial pen mods

    Below details the GPU vcore measure point. Use this to measure/check the voltage throughput for the GPU core.


    The image below details the first two steps of the VGPU volt mod. To raise the vcore from stock 1.35v to 1.4v, connect the two solder points marked with the red line using a conductive ink pen.

    After having done the first connection (red line), you can further raise the vcore by making an additional connection between the solder points marked with the blue line. This will effectively raise the GPU vcore to 1.5v


    Continue the GPU vcore modding on the next page if you're feeling the vibe of insanity. You can move from this point onto the memory voltage mods if you feel 1.35v or 1.4v is sufficient for your needs.

    Solder and pen mods, into the insane

    Now if you're really feeling the urge to make your card yelp in pain and then perform like a bat out of hell, follow the guide below.

    WARNING: We advise that anyone who uses steps 3 and 4 of this guide should be running at least water cooling on the GPU core.

    Follow the steps outlined below to reset the card's stock 1.35v GPU vcore to a "stock" 1.65v by replacing the resister outlined in blue with a 50k ohm resister. Additionally, to allow the full volts to travel to the core, the OverCurrent protection hardware feature can be removed by removing the resister outlined with the red square.


    Now the connection of the solder points from Step 2 now have new values within step 4. Following the same guideline as in the original processes of Step 2, the first join point marked in red now has a value of 1.7v rather then the original 1.4v. To up the anti yet again after having already done the 1.7v connection, the connection between the solder points marked in blue will give 1.8v for the GPU vcore.


    Now that you have a whopping 0.45v above stock vcore running to your GPU core, look to the next page for the memory voltage mods to round out your overvolted overclocking mayhem.

    VMEM measure point and pencil or solder mod

    Step 5 clearly marks the memory voltage measurement point, or VMem-measure as it's commonly called.


    Step 6 outlines the methods to increase the VMem (memory voltage). Two options are available for this and both are equally effective. One option is to simply shade the resister using a 2B graphite pencil to lower the resistance of the resistor and effectively feed more volts through, in this case it leads to the memory. This will involve trial and error whilst testing with the digital multi meter (DMM) to check the voltage. This method is easy but less accurate.


    Step 5 clearly marks the memory voltage measurement point, or VMem-measure as it's commonly called.

    Step 6 outlines the methods to increase the VMem (memory voltage). Two options are available for this and both are equally effective. One option is to simply shade the resister using a 2B graphite pencil to lower the resistance of the resistor and effectively feed more volts through, in this case it leads to the memory. This will involve trial and error whilst testing with the digital multi meter (DMM) to check the voltage. This method is easy but less accurate.

    The alternate method is to solder a 20k ohm variable resister (VR) to the IC leg indicated in the image and a grounding point e.g. the metal back plate. This will allow more accurate tuning of the memory voltage throughput, but obviously involves more time to do the mod as well as higher level skills.

    The 8600GTS is a good introduction to volt mods as it allows for the three main types of volt mods to be performed on a single card. Not only that though, the card overclocks exceptionally with these mods in place.

    So there you have it, a VGPU mod for 1.4v, 1.5v, 1.65v, 1.7v and 1.8v as well as a VMem mod that allows the gradual increase above the stock 2.1v.

    The actual overclocking!
    Coming up next we put the volt mod to the test, seeing how far the 8600GTS will go. We're getting some custom extreme cooling gear fabricated, as soon as that comes in we'll get to work pushing the card through the roof.

    Stay tuned for that exciting chapter. Until then, take care, have fun and go nuts!

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