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View Full Version : Gigabyte 8600GTS vmod ?



ol'norton
01-05-2008, 11:48 PM
The back of the Gigabyte Silent Air 8600GTS only has two chips that could be PWM Controllers, a 74ACT08 (printing is too small, looks like an F, maybe Fairchild :scratch:)
& a NEXSEM NX2114. This 2nd one I think is the Vmem (I've got a 50/50 chance anyway) Assuming it is, the pin highlighted in green, is the FB pin #6.
The dot in the red eclipse closest to it has no resistance to the #6 leg, the other has no resistance to ground. So a pencil mod here should raise the Vmem.

http://img174.imageshack.us/img174/1285/8600gts003cropnt1.jpg http://img138.imageshack.us/img138/6207/nx2114xq0.jpg


I got this diagram from the NEXSEM website. But if #6 is the FB undervoltage protection,
Shouldn't I get some resistance to earth?
It reads an open circuit. :scratch:

2nd problem: Where do I read the Vmem?
There is nothing on the top of the board that looks like an inductor. :scratch:

http://img174.imageshack.us/img174/3392/8600gts014nu5.jpg

http://img174.imageshack.us/img174/1991/8600gts015sq4.jpg

boshuter
01-06-2008, 10:25 AM
Here is a link to some 8600GTS mods on VRzone. They aren't on a Gigabyte card, but probably the same or close enough to maybe help you out.

http://www.vr-zone.com/articles/NVIDIA_8600GTS_Overclocking%21/4875-2.html

ol'norton
01-06-2008, 11:49 AM
Thanks Boshuter, but those cards have completely different componants than the passive cooled models.
Not the least, mine has no additional power lead, & gets all it's power from the PCI-E slot. So I wouldn't be able to run those sort of voltages anyway.:(

ol'norton
01-06-2008, 11:59 PM
Well I think I have the Vmem worked out. The spot in the pink square is the easyist of 5 places to read what I think is the Vmem.
It read 2.083v which seemed a bit high for stock, but nowhere else came close.
A couple of spots read 1.435v, so I assume that's the read point for the Vgpu.
I took out my trusty HB & penciled a bit on the resistor in the red eclipse. It raised the voltage in the pink square to 2.156v.
I need to change the Silent Air cooling & put some ram sinks on the memory to really test it out,
but I was able to get through the trolls in 03 with an extra 30mhz. So I think I'm on the right track.

http://img518.imageshack.us/img518/3808/8600gts003cropmeh5.jpg

boshuter
01-07-2008, 07:54 PM
Good job John......:thumbs:

That memory voltgage sounds right, I think on that other card I linked to the default mem voltage was 2.0-2.1v. I've had mixed results with raising mem v on gpu's, biggest gains always came from vgpu for me.