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GeForce 8800 GS/GT/GTS Voltmods

Discussion in 'Articles' started by largon, Feb 28, 2008.

  1. infrared New Member

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    Because of the block of smr's. The other sides have capacitors which aren't used for setting VID values.

    I'm 99% sure, but i'll double-check tomorow with the datasheet.
     
  2. dd051 New Member

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  3. quadomatic New Member

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    I'm not sure what the default voltage of the card is. Do you know?

    [​IMG]

    I'm looking at that picture to determine default voltage and which resistor connections go to which pins.

    It LOOKS like VID1 and VID6 are the only pins that don't have resistors, so those pins aren't connected to anything (meaning 0 I guess?), so I guess the default voltage is 1.11875V.

    So, it looks like in order to raise voltage, do you not remove resistors and bridge gaps, but just remove resistors and leave gaps? That appears to be the way it is, since VID1 and VID6 lead to pads that aren't connected - the traces just lead to solder blobs that would hold a resistor, but those blobs aren't connected.

    How much could i raise voltage to? Would 1.3V be safe on a dual-slot air cooler?

    I could hit 1.31875V by simply removing the resistor on VID3 (on the chart, it has 1's accept on VID3, VID1 and VID6 for that voltage. So would I be correct in saying that 1's are connected, and 0's have gaps that aren't bridged?

    Would removing resistors and bridging gaps be safer? That way I'd be able to test a different voltage that would be lower. I wouldn't be able to attach resistors...are they necessary to make sure I don't fry the chip?

    I think this is the proper layout. I labeled the pins as well as the resistors they trace to:

    [​IMG]
    [​IMG]
     
    Last edited: Nov 16, 2008
  4. quadomatic New Member

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    Someone else did a pencil mod by following the FB pin to the resistor it connects to and shading the resistor. It increased the temperature by 6 degrees Celsius. Based on the change in resistance after doing that, I'm guessing the voltage after the mod was 1.165V. Raising voltage to 1.32V might be problematic.

    So, maybe I should shoot lower?

    Or wait...I don't think that would work. The idea isn't to shade over the resistor with the VID resistors but to remove them and make a gap in the connection. Right?
     
  5. infrared New Member

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    yep basically.

    We really need to find a vgpu measure point before you start playing, but tbh i have no idea where to start looking.
     
  6. quadomatic New Member

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    I see...

    http://www.xtremesystems.org/forums/showthread.php?p=3436333&posted=1#post3436333

    Should probably look at that thread. panzerchaos47 has 2 9600GSO's that he's testing with. GPU0 has no pencil mod, and GPU1 was modded using the FB pin.

    He labeled a point he's attempting to use to measure voltage:

    http://i256.photobucket.com/albums/hh166/hitokirixii/9600gsomeasurepoint.jpg

    I don't think that's likely the actual point though, and neither does he, since it registers 1.25V on idle w/out pencil mod, and BIOS limits voltage to 1.1V by default, and based on the VID diagram I figured the voltage is 1.11875V.

    Either way, it seems to accurately predict the change in voltage.

    On idle, the card without volt mod is 1.25V, and with volt mod, is 1.32V (this is just the READING, probably not accurate voltage, but that shouldn't matter since we know default voltage...aren't we just concerned with voltage change?)

    Based on calculations of resistance changes measured with the multimeter, the voltage change should be about +.07V...and 1.32V-1.25V=.07 So....I guess that point is at least reliable for measuring CHANGE in voltage.

    Does the change in voltage using the FB pin depend on the thickness of the shading over the resistor?
     
  7. quadomatic New Member

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    I decided to try the FB volt mod. It doesn't seem to be producing the desired effect. I had to lower clock speeds back on the memory. Maybe I shaded to thick? It seems like the gpu is hotter than it used to be...is 64 odd?

    Maybe because I didn't reapply thermal grease properly? I just shaved off the dried paste that was on the heatsink before and threw it back onto the core. Probably has some burn in time, but still...

    Maybe the added voltage requires a better cooler because of the extra heat?
     
  8. quadomatic New Member

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    I took the cooler off and looked at the core, and I found that the thermal compound wasn't exactly working as I planned...so yeah. Looks like reapplying thermal compound is a little important. It was all dry and bunched up.

    Regardless, I ordered an Accelero S1. I'm going to attach that to the card, with a 120mm fan ziptied to it. That should help significantly.
     
  9. infrared New Member

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    The accelero comes with some really nice thermal paste pre-applied (AC MX-2), but if you need to remove it again, get a tube of it and apply it fresh. I would also highly recommend getting some Arcticlean.
     
  10. quadomatic New Member

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    Good to know.

    Now I just have to wait till...Tuesday for it to show up. Dang UPS is slow. Everyone should just use USPS (in the United States anyways...). Saves a lot of cash and its wayyyyyyyy faster. Would've been about $5 flat-rate and it would've gotten here in 2 days.
     
  11. maynardx New Member

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    Hello everyone
    As far as I'm newbie in electronics, I'd like to ask You, which resistors exactly should I buy for EVGA 8800GTS KO Version? I will appreciate all Your help Guys.
     
  12. quadomatic New Member

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    http://www.xtremesystems.org/forums/showthread.php?p=3472814&posted=1#post3472814

    Someone has tried removing the resistors that were connected to the pins for voltage, but it made absolutely no change. Are we sure those are the voltage pins? Is it a different side of the chip that's for voltage?
     

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