IC7 Vmem mod fluctuation

[gingeralenz]

i did the vmem mod removed the r50 resistor and first of all tried the multi-turn trimpot. I got to 3.2v fine but the ddr and vtt voltages were fluctuating alot. So i tried fixing a 330 ohm resistor thats fine voltage is stable, then tried a 390 ohm fine. Went up to a 470 ohm resistor and i got fluctuations. So at the moment i have the 390ohm resistor soldered on but it only gives me a max vdimm of 2.91v.
Anybody got some ideas why the fluctuations are happening id like have 3.2v max.

[CATCH22ATPLAY]

Hm maybe a resistor divider network would have been the best way to do this mod. Since a resistor divider network is referenced to ground that should stop the fluctuations. Hmm my IC7 is semi fried so maybe i can look into this. Mine works but i can't set any freqs at all and all my cpus will only run at 1/2 speed. DAMNIT!!!!! Oh well the price i pay for using subzero cooling. I loved that mobo. Bastard did 305fsb and i can't get my P4C800 or Albatron mobo to get anywhere near that high If i find time or the inclination to try this experiment i'll post results about it. If you want to experiment here's how to do it. Look at R50 after removing that resistor. We are going to add 2 resistors which i'll call R1 and R2. Looking at the mobo like it's installed in a case. We'll first want to solder one side of R1 to the bottom of R50 trace and one side of R1 to upper trace. Now solder R2 to ground and to anywhere between lower trace and R1. But NOT to top of trace or between top of trace to R1. Very important you do it just as described. Now if i can pull my head out of my arse i'll try and work the math. OK what's default VDD anyways? 2.65? I'll assume so.
-EDIT-deleted-Wrong equation doh!!! see my 3rd reply


Oops i just remebered we are actually trying to trick the hardware monitor chip into thinking it's not putting out enough volts and that it needs to raise volts. So maybe swapping R1 and R2 in the equation would actually be the correct way to do it. Like this instead.

-EDIT-deleted-Wrong equation here too doh!!! see my 3rd reply

Now since i'm not positive of any of the above i just wonder who's got the balls to even try it

[Nohto]

It doesn't really make sense. You say solder one side of R1 to bottom trace and then one side of r1 to upper trace. How many sides does r1 have? That would be just soldering r1 into the r50 location.

Now solder R2 to ground and to anywhere between upper trace and R1

How do you solder between a resistor? Do you mean solder it to the upper part of the trace. The upper part of the trace is ground. and the lower part of the trace actually connects to the resistor right next to it, where the upper part of that resistor connects to ground also.

[Nohto]

pic courtesy of MnM

[CATCH22ATPLAY]

There are 2 sides to a resistor no? In my mind i'm picturing a resistor with 2 inches of wire on each side. Or telephone wire soldered to the traces of R50 and resistors or Variable resistor/s soldered to the end of the wires. That pic is perfect btw. The resistor you solder to R50 is perfect. That small capacitor next to it the top of it is ground. So take that piggy back resistor you got on top of the resistor on R50 and solder from the bottom of that resistor to top of that capacitor. Only problem i see is that this may not work if R50 actually goes to a mosfet gate driver. But it's still worth a try.

My edit was to correct R2's placement form bottom of R50 to top of MC64 would be perfect.

[Nohto]

That's not my mod. I removed the resistor from R50 with no problem, but after I soldered a wire to the lower pad I caught it and ripped the pad off. I then proceded to trace where that pad was attached to and discovered a tiny trace from the resistor next to it. I then Ohmed out the upper pad to a MB mount ground and found it wasn't a perfect contact, so I searched around and found the mosfet location to be a good contact with no resistance.

[gingeralenz]

heres how my voltmodd looks now

[CATCH22ATPLAY]

Damn i must have been stoned when i was doing the equations above. OK ignore everything i've said before. Use the same example i wrote before about placement of R1 and R2. Also we are lowering volts to get hardware monitor to increase volts. Everything is the same except the equations. Which is as follows:

V out = V in * [R2/(R1+R2)] see difference below

V out = 2.65 * [R2/(R1+R2)] see difference below

V out = 2.65 * [10,000/(300+10,000)] = 2.573 a diff. of 0.077 which should increase actual VDD to 2.727

V out = 2.65 * [5,000/(300+5,000)] = 2.50 a diff. of 0.15 which should increase actual VDD to 2.80

V out = 2.65 * [2,000/(300+2,000)] = 2.30 a diff. of 0.35 which should increase VDD to 3.00

V out = 2.65 * [1,500/300+1,500)] = 2.21 a diff. of 0.43 which should increase VDD to 3.08

V out = 2.65 * [1,000/(300+1,000)] = 2.04 a diff. of 0.61 which will increase VDD to 3.26

You will notice i never increased the value or R1. That's because most people start running into problems when R1 is close to 400 ohms. So i just left R1 at 300 ohms. I think this will take care of voltage fluctuations.

Now what i'd really suggest is using a fixed 300 ohm resistor for R1 and a 10k ohm Variable resistor for R2. Set it for 10k ohm and see wtf happens. I don't think you'll need to worry about frying anything doing that. OK more dudes with balls needed. Oh and sorry about the wacked out equations earlier and heck they still may be wacked I been out of school for 20 years. So give me some slack.

[LikwidKool]

Originally posted by CATCH22ATPLAY
OK more dudes with balls needed.

I wish I had some, because I would love to stabalize these volts more at higher vdimm. Above 3.0v my stuff gets squirelly.

[[SLC]Tachyon]

Turn the pot to 0k ohms, and then max out the memory voltage in BIOS, then adjust the pot. I've heard that this may help stabilize the VDIMM/VTT.

[LikwidKool]

hmm, that sound like a plan. Only problem is I crazy glued the vr to one of my pci slots so it would be tough to take it off and re adjust to 0ohms. I believe I first started out at 300ohms at 2.5 and went up from there.

[[SLC]Tachyon]

Pry the pot off the slot and mount it with the screw facing upward so that you can adjust it more easily.

Also- I have heard that the quality of Radioshack's pots arent that great and that they supposedly degrade after time. Maybe try another pot, or better yet a fixed resistor?

[LikwidKool]

The screw is facing out for easy adjustability. It's just that I thought when it is hooked up, the ohm reading will be off. From what I thought I understood, the pot would have to be totally disconnected in order to measure a correct reading. That is why I thought it needed to be taken off since resoldering the wires back on where it is now would be annoying.

As far as Rat Shack pots, I had haerd that the more you adjust them, the more they degade too. Personally I have been ok so far, but only have a few vmods in my bag of tricks so far! Plus I try not to play with it too much. I got it right now to 3.0 when set to 2.8 in the bios, and that is about as high as it will go without fluctuating more than I would like. I will look around for better pots in the future.

[CATCH22ATPLAY]

Well since i'm so dissapointed with my asus p4c800 deluxe and my albatron mobo. Damn my ic-7 rocked before i killed it. Well i just got another ic-7. I'll try to see about this stability thing. I know i had to use a switch to start with vmem at 2.90 or so and after i booted i flipped my switch to get 3.20 volts. Worked just fine for me. Without doing that i couldn't get mobo to start at all. So try sticking a 100 ohm resistor with a switch in parallel with your vaio reststor. Turn switch on for lower volts and when comp starts turn switch off for higher voltage. But i'm still in a mind to try the mods i mentioned before. If i ever get the time i'll get around to verifying them. I haven't turned my comp on in about 1 1/2 weeks. Just too damn busy lately. Hoping for a bit less of a schedule shortly.

[BioBlade]

gingeralenz wat kind or risistor are you using on your mod ?>

[CATCH22ATPLAY]

OK it looks like after checking out my MAX3 that they are using our ideas for volt mod. However i believe MC64 should have been replaced with R2. So the mod we did before was correct. Except now just remove R50 and MC64 and use my R1 and R2 resistors in my equation in the place of R50 and MC64.