wtf is going wrong with the vdd mod?

[-FireBurn-]

I did the vdd mod yesterday on my 9500np with a 2.7kohm resistor, and the voltage raised >4v ?! I did the vgpu mod before with an equal resistor and it worked without problems (1.5 -> 1.75). What is going wrong here, the vdd voltage should be ~3.2 and not >4

[saaya]

vdd? vdd is chipset voltage, your talking of vmem and vgpu right?

you cant take the same resistor for both unless they are vrs. resistors dont increase the voltage by a certain amount in percentage... the vr doesnt increase the voltage by 0.25 whatever the default voltage is either.

you need to calculate what resistor you need for how much voltage, in contrast to the default voltage. use vrs, theyre much better for fine tuning anyways.

[-FireBurn-]

yes vmem. But on xbitlabs they have also used 2.7kohm for vgpu and 2.7kohm for vmem. Or do I have to do the vddq as well?

[zachsss626]

Wow, over 4v. You sure nothing is shorted? It sounds to me like the mod is behaving like there wasn't a resistor at all. Current going straight from the FB leg to ground without any control resistance would definitely cause >4v.

[-FireBurn-]

Yes, it was above 4V. I startet Windows and there weren't artifacts o_O. I was even able to run 3dmark without artifacts. I have passive aluminium-coolers on my memory, and they were as hot as always. I don't know.
I will try the mod again and if it's above 4v again I will take a picture of my Multimeter with my webcam.

[zachsss626]

Hmm... if you only had the mod on for a short while, there's a fairly good chance that something was a little off kilter with it, and it got fixed when you took it back off. Vdd isn't a notorious card killer like vref, so running it for a while at 4v and with some ramsinks wouldn't cause damage. Vdd does tend to cause artifacts when it gets too high though... at least it did on my 9500 w/ Hynix 3.6 ram. What kind of ram do you have on your card?

Edit: 2.7k :slobber: that does seem extremely low for vdd. If you go here (http://www.thecrucible.ca/forums/viewtopic.php?t=83) they tell you to use a 20k trimmer for the mod. I would go pick up a couple 10k trimmers from radioshack (they don't carry 20k that i know of) and hook them up in series, using pins 1 and 3 on one of the trimmers and 2 and 3 on the other one. That sets it up with full resistance on the first and variable resistance on the second. You could also just find a 10k fixed resistor to take the place of that first pot, it doesn't matter.