View Full Version : 8RDA+ Vdimm mod guide, expert read through needed!
k1114
03-06-2003, 01:19 AM
I have written the first half of my vdimm mod guide, which to be honest, is basically a spread out and simplified version of the poster type picture in the vdimm mod thread found in this forum. That poster guide really is a great resource, but it is a bit cluttered and it lacks the VBT section of the mod. (I still am not sure who made the image so I can give them credit, it was posted under different names on different forums)
I really would like someone who has done the mod to give it a read through to see if I messed up the guide at any point, and I am still not sure what resistance is needed for the VBT part of the mod, so I have not been able to add that yet. I have not linked to the page internally, it's just been uploaded so that the guys here could take a look at it. link (http://www.8rdafaq.com/vdimm_mod.htm)
Nohto
03-06-2003, 01:59 AM
muzz
Wooooooooooo boy!!! We are talking vdimm here, not the vdd.
Here is what Jeff said, and he's done it.
"What resistance are you adding across the cut trace? You should be starting at ZERO Ohms and then working slowly up. Vdimm will top out ~300 Ohms at 3.2x volts and if you add too much resistance, strange things could be happening. I know my BIOS, MBM, and USDM all don't like when I have too much resistance."
If you cut the trace I believe you have to start at 0. You would not want to add a 10 ohm resistor inline. That's the way I understand it.
Holst
03-06-2003, 06:42 AM
I think you need to do the mod m8, as some of that is wrong...
You dont want a resistor is line with the VR as you want to start at 0ohms and work up, so to disable the mod you just set the VR to 0.
Your scale for the calculated VDDR is wrong, the Vreg stops increaseing the votlage at 3.14v, I dunno why but mine did...
So to set the mod up, set the VDDR to 2.9v then increase the VDDR with the pot untill it maxes out and go no further. This way you can still use lower voltages by changing the bios.
The bios wont show any VDDR increase so you need to measure with a multimeter, one of the legs of Q32 is VDDR (ill look later on for which one if you like)
I think I used a 500ohm cermet pot on mine, although I cant remember exactly..
k1114
03-06-2003, 11:22 AM
Allright, so the as the resistance raises, the voltage raises? I see why 2.9v should be the voltage to work from now.
And the 10 ohm resistor really isnt nessecary?
The big problem with this mod is that everyone seems to do it a different way. I wouldn't even bother with it, but I keep getting requests for a clear guide on it :(
k1114
03-06-2003, 03:19 PM
Originally posted by MickeyMouse
two ways cut trace lift leg and use a 100ohm VR set to "0" and increase resistance to raise ddr. the 10 ohm no isn't needed.
hmmm... I wonder if there is a proper forumla to calculate the resistance/voltage :(
k1114
03-06-2003, 07:10 PM
Add preliminary VBT, but still not sure exactly what resistances are needed, or where to measure vbt voltage.
bowman1964
03-06-2003, 07:52 PM
Originally posted by k1114
Add preliminary VBT, but still not sure exactly what resistances are needed, or where to measure vbt voltage.
ok see if this helps
k1114
03-06-2003, 08:51 PM
thanks bowman :)
now all I need is what resistance to use for the vbt, and maybe some sort of basic idea of what resistances give what for both vbt/vdimm (maybe some sort of formula? :confused: )
edit: thats the point I have down for vdimm voltage! wow, the poster guide really was messed up!
k1114
03-09-2003, 05:07 PM
I've re-written the guide with the help of a guy from cpumods.com who has done it personally. I'd appreciate another read through
Holst
03-10-2003, 06:31 AM
Nice 1 m8.
Thats the best guide on the net now.
Wired in slightly different places to my own (I think everybody did it differently)
If I were you id specify 1k multitern cermet pots as opposed to just variable reistors as using a multitern is so much safer than a big ol VR that is easily knocked.
k1114
03-10-2003, 11:37 AM
Originally posted by Holst
Nice 1 m8.
Thats the best guide on the net now.
Wired in slightly different places to my own (I think everybody did it differently)
If I were you id specify 1k multitern cermet pots as opposed to just variable reistors as using a multitern is so much safer than a big ol VR that is easily knocked.
cermet pots? I thought those were variable resistors?
bowman1964
03-10-2003, 11:50 AM
Originally posted by Holst
Nice 1 m8.
Thats the best guide on the net now.
Wired in slightly different places to my own (I think everybody did it differently)
If I were you id specify 1k multitern cermet pots as opposed to just variable reistors as using a multitern is so much safer than a big ol VR that is easily knocked.
Yes Holst is correct...you see there are many differant types of vr resistors proper term(Potentiometers) there are the cheap pot type that so many people use. and but one bump and it can change lots...then we have mutiturn trimmer Potentiometers that work the best ,they come in 10 turn and 15 turn versions.i use the 15 turn models.these have a much finer adjustment and are more accurate.
bowman1964
03-10-2003, 11:58 AM
I should show everyone who does'nt know what a standard pot type Potentiometer looks like.;)
hempp
03-10-2003, 12:26 PM
i need use 1k vr or 10k vr for vddr mod???
k1114
03-10-2003, 01:08 PM
Originally posted by hempp
i need use 1k vr or 10k vr for vddr mod???
1k
hempp
03-10-2003, 01:39 PM
tkz 1k = 100ohms?