^This spot-to-GND is essentially the same as spot2/spot3-to-spot4 in this pic:
I'm pretty sure we're talking about the right soldering spot for the vGPU mod... But here's a safer (it's not a populted SMD solderpad) and much easier soldering point:
Last edited by largon; 10-30-2007 at 11:15 PM.
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11Ω (or 15Ω?) between vSense pin and ground is a horribly low resistance. I was expecting something around 45Ω since G80GTS/GTX which measures to 35Ω output 1.28v, and since the GT has lower vGPU thus the sense resistance should be higher than those on GTS/GTX as all use the same PWM IC. <20Ω is very low and IMO somwhat suspicious...
If someone is willing to be a guinea pig then I would suggest soldering a 500Ω multiturn VR between this point and ground. Before soldering measure the resistance between soldering points (should be ~15Ω), set VR at max resistance (500Ω), solder the VR, measure resistance between soldering points (should be ~14.5Ω, if much less don't turn the card on) tune down for more vGPU.
Last edited by largon; 10-30-2007 at 11:17 PM.
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Easiest soldering point for vGPU mod:
^This point to ground, 500Ω VR at max, tune down for more vGPU.
Be sure to measure the resistance before and after soldering before powering up.
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Does the 8800GT card have the same layout as the 8800GTS or the 8800GTX?
I haven't seen pics of it without cooler yet...
-edit- never mind
Left card:
http://www.xtremesystems.org/forums/...68#post2523668
Last edited by Garrett; 10-31-2007 at 03:17 AM.
lol... This forum requires that you wait 70 seconds between posts. Please try again in 8 seconds.
*phone rings*
Friend: Do you have a spare PSU lying around?
Me: No why?
Friend: My PSU just blew up, I think the second 8800GTX might have been too much for it to handle
Me: what PSU was that again?
Friend: Antec 480w
Me:........
The vGPU mod needs beta testing but otherwise the mods are technically the same as for 8800GTS/GTX only the tracing and solder points differ. Unfortunately pencil vGPU mod doesn't seem to be possible - unlike it was first thought.
!WARNING, BETA, UNCONFIRMED!
Reference 8800GT 512MB vGPU, vMEM, pencil vMEM mods
!WARNING, BETA, UNCONFIRMED!
Last edited by largon; 10-31-2007 at 08:32 AM.
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Coding 24/7... Limited forums/PMs time.
-Justice isn't blind, Justice is ashamed.
Many thanks to: Sue Wu, Yiwen Lin, Steven Kuo, Crystal Chen, Vivian Lien, Joe Chan, Sascha Krohn, Joe James, Dan Snyder, Amy Deng, Jack Peterson, Hank Peng, Mafalda Cogliani, Olivia Lee, Marta Piccoli, Mike Clements, Alex Ruedinger, Oliver Baltuch, Korinna Dieck, Steffen Eisentein, Francois Piednoel, Tanja Markovic, Cyril Pelupessy (R.I.P. ), Juan J. Guerrero
I hate to say this but it's possible nVIDIA somehow prevented vGPU vmodding by some nefarious board design feature. If the vsense pin doesn't react to resistance changes it certainly doesn't look good...
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Indeed, but I think not many have the time available to search for ultimate timings for their card, having predefined sets works easier. On the other hand, the extra gain is rather small. If you are 2 3D Marks away from the world record, I might want to put effort in it, otherwise I would just neglect this feature.
Coding 24/7... Limited forums/PMs time.
-Justice isn't blind, Justice is ashamed.
Many thanks to: Sue Wu, Yiwen Lin, Steven Kuo, Crystal Chen, Vivian Lien, Joe Chan, Sascha Krohn, Joe James, Dan Snyder, Amy Deng, Jack Peterson, Hank Peng, Mafalda Cogliani, Olivia Lee, Marta Piccoli, Mike Clements, Alex Ruedinger, Oliver Baltuch, Korinna Dieck, Steffen Eisentein, Francois Piednoel, Tanja Markovic, Cyril Pelupessy (R.I.P. ), Juan J. Guerrero
As it happens I don't have the card, yet. So I haven't done any soldering. :\
But it doesn't matter what point the VR is soldered as long as the solder point is directly connected with the sense pin.
There are atleast 4 points that could be used for soldering the VR - if the mod worked that is...
You were not supposed to see this.
Coding 24/7... Limited forums/PMs time.
-Justice isn't blind, Justice is ashamed.
Many thanks to: Sue Wu, Yiwen Lin, Steven Kuo, Crystal Chen, Vivian Lien, Joe Chan, Sascha Krohn, Joe James, Dan Snyder, Amy Deng, Jack Peterson, Hank Peng, Mafalda Cogliani, Olivia Lee, Marta Piccoli, Mike Clements, Alex Ruedinger, Oliver Baltuch, Korinna Dieck, Steffen Eisentein, Francois Piednoel, Tanja Markovic, Cyril Pelupessy (R.I.P. ), Juan J. Guerrero
What really bugs me is that those 2 resistors connected to the vsense pin don't appear to ground with the actual ground plane which is just a quarter of a millimeter away from the resistor, instead both traces end in copper vias and dive into the PCB. I wonder where those traces really ground...
edit:
Here's a pair of pics to compare the vsense network on G80GTS and G92GT, they're physically almost identical if the layout difference isn't considered (left=G80GTS, right=G92GT, red color=vsense):
Last edited by largon; 10-31-2007 at 11:02 AM.
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Got some good news and some bad news.
Bad news is, the variable resistor I've laying around seem to be dying
Good news: this is what caused the modification not to work. Had some more time today to find out what really went wrong, just got another VR on it today é voila, variable GPU voltage
No need for me to paint it out, Largon's picture is allready clear enough, VSEN+ to ground
Have fun
wittekakker,
Awesome!
I was really beginning to worry since first impression was it didn't work, I just couldn't see another way to do the mod and ofcourse since the mods are almost identical to those on 8800GTS/GTX it really put me off.
Whew!
Anyone planning on executing the vMEM mod? Good to know that.
Thanks!
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