Alternate way to do the VFSB mod for the Abit AS8.

[Kunaak]

I didn't come up with this mod myself, it was with help from 2 of the better volt modders around here, that came up with this idea for me, I was just the helper monkey willing to risk my board for a easier way to do this particular mod.

I did it a few weeks ago, and just havent had a chance to get a good picture of it, to show how it was done.

with this way, you need no soldering or a extra resistor between the two solder points, just solder to the 2 points shown, and ground it with the 3rd leg to the extra hole, that happens to be blocked by the IDE port...

anyways, I know the pics aren't perfect, but they are all I can get.
I had to borrow my friends digital camera, and this was about as good as I could get these pics, hopefully, people can get a better idea on how to easily do this mod.

I used a 5K VR on this mod.
that not nearly enough at all.
if I were to redo this mod, I would try it with a 100K atleast.
see, this mod is insanely sensitive.
at first it will look like it's not doing anything...
then you will come to a point where 1/8th of a single turn will take you from 1.23 volts, to 1.73 volts almost instantly.
that one 1/8th tiny turn is extremely sensitive, and can adjust your voltage extremely fast with the 5K.

oh yeah... the mod is also backwards...
meaning, counterclockwise for more voltage, clockwise for less...

it's abit of a weird mod, but once you get it right, it's nice to have such a range for your VFSB Voltage.
I have had it up to 1.75 volts with no problem.
even had it up to 2.0 volts by complet accident...
but then the motherboard doesn't boot, if you reboot.
so somewhere around 1.7 volts, the mod will make the motherboard stop booting, in which case you need to turn it back down (clockwise) for less voltage.

[crotale]

Just to double check with you Kunaak:
You started with a 5k VR but would recommend a 100k if you would redo it?
I'm just wondering because that's quite a big difference...

[Malves]

The trimmer may be working backwards because of the 3rd leg being grounded. You probably don't need to ground that.

Also if you think 5k is too sensitive, then you need to get a trimmer with less resistance, not one with more. A 100k trimmer will make it even more sensitive.

I believe that a 2k trimmer will be good enough for this mod.

I've been thinking in getting this board and full mod it, including vdimm, to take pics for my site and then get rid of it.

[crotale]

Also if you think 5k is too sensitive, then you need to get a trimmer with less resistance, not one with more. A 100k trimmer will make it even more sensitive.

That's what I was thinking too...

It would be interesting to know if the ground is needed or not.

[CaTalyst.X]

The 3rd leg is grounded to imitate the parralell circuit i think.. kinda like on the IC7 mods. Without the grounding, you need the fixed res.

-CaT

[Kunaak]

without the 3rd leg grounded, the mod does nothing.
believe me, thats what I tried first, before doing 3rd leg soldering job.

a 2K for the job?
wouldn't that make it insanely sensitive, like 1/20th of a single turn will take you from the 1.23 to 1.7 instantly?

the mod for a few turns will do nothing, the all the sudden it will jump really really fast, in less then 1/8th of a single turn, then it tops out, and stops doing anything again, once it reaches the max voltage...

wouldn't a 100K or so, allow you to get to that point where the mod, would become useful again, and allow you alteast a few turns to adjust the voltage, instead of a super small 1/8th turn?

this is a weird mod indeed, takes some getting use to, but it works great, once you get use to extremely fine adjustments.
this mod was very useful to get a higher 1:1 stable.
with it at 1.23 volts, I can barely get 245 at cas 2-2-2-5 stable, but when I pushed it to 1.6 volts, I got up to about 265 nice and stable. but then again, I had so much voltages out of whack, that it might have been something else

[sin0822]

Ok um the 2k would work better than the 5k. Why? I guessing here. Lets say in theory the 2k is 15 turns and so is the 5k, then you have more turns and more accurate res between 0-2k, but then you have less accutacy because of less turn going from 0-2k. You just have to have a different mindset, i might try this mod.

[crotale]

Things are definitely complicated. On one hand higer resistance would yield a great span of voltages, but, the the way the mod is done here the VR is acting as two resistances. (I mean, instead of a fix resistance, one part of the VR is acting like that.) And chosing a lower resistance VR on the other hand would be able to cause dangerously high currents.
So it is really hard to choose a suitable VR in this case IMO.
(maybe a exponential VR would be something )

I have the board at home, but I won't be home and capable of modding it until the middle of June, but I will use a fixed resistance instead. This way, the mod will not be that sensitive if the values are choosen well.

If people are scared (I would be) to solder a SMD like Hipro did, I recommend just soldering two wires to the spots and then put a larger resistor on the wires, like I have done for vdimm on this IS7:



Full size:
http://www.nordiccrew.com/crotale/vmod/modoverview2.jpg

[persivore]

Does the voltage suddenly start to increase after you get to about 1/2 of the variable resistors resistance?

[Kunaak]

what happens is this...

I have a 25 turn VR's.

after about 10 turns, it does absolutly nothing.
then on the 11th turn, the voltage can go from 1.23 volts, to 1.73 volts, in a super small span of a single turn, like 1/8th of a turn.

then after that, it tops out, and then the other 13 or so turns do absolutly nothing again.

so a very small part of the VR does alot for the voltage, then it doesn't work anymore.
but this small range, gets me a voltage range from 1.23 to 1.7+ volts.

[{PMS}fishy]

What exactly does this mod acomplish? I have only had time to play with my AS8 for 10 mins, and there are a few more mods that need to be done to the MB.

From what Hipro was saying, vAGP made the biggest difference. Im still lost on this mod. Please clue me in.

[Kunaak]

helps stabilize very high FSB's.

[persivore]

Have you tried the mod without the top wire connected to the variable resistor, and just use the middle connection and ground?
I think that the problem is that there is too much resistance between the top 2 pins on the variable resistor (the pins connected to the Vdimm regulator SMD's), and this is only overcome when there is enough resistance between the middle pin and ground to increase the voltage (hence why there is a sudden increase in voltage). You might need to use a higher value variable resistor if you try the mod a different way tho.

[Kunaak]

Have you tried the mod without the top wire connected to the variable resistor, and just use the middle connection and ground?

No I have not.

honestly, the mod works for me, and I have already solderd and resolderd this mod 4 times, and last thing I want to do is wear out the soldering points, cause I've made that mistake in the past and killed the board.

I'll deal with a weird working mod, and let someone else build on this mod better if they want.

I am sure theres a better way to do this mod, all I am trying to show here, is with this way, all you need is a VR and a steady hand incase you can't find the odd resistor thats required for the other way, or if you want more then 1.33 volts, like the the other way seems to be limited to.

with this method I have had it pretty damn high, and the boards taken it just fine.

not that I care to be running 1.7 volts for the VFSB on a daily basis

but I have been running it at 1.4 volts for about 6 weeks now, and I can say its had no bad side effects yet.

[{PMS}fishy]

Works pretty well. I used a 10k, and it sure is senstivite.

Ill redo the mod later, and check the resistance of the pot.

I think a fixed resistor and a pot would be best for this mod, it doesn't take very much to get it to respond at all.

[nCrusader]

*EDIT*

Just read Kunaak's report on Hipro's way...

Problem is, I don't have a 10k... I'll try a 20k.

BRB

[crotale]

Kunaak: How was the VR adjusted from the beginning? 0 ohms between which legs?

[sin0822]

well i did the soldering finally, and it boots up fine. Now i need a resistor, what you guys recomend? 5k or 1k fix and 1 k VR? Can you guys find out at what Resistance it jumps? Also how should i hooke the VRs up if i use 2?

BTW that solder spot was tight.

[sin0822]

its relly a wierd mod, becaus ei though this increase your fsb/agp voltage? This only effects my fsbvtt? Is that right?

[dippyskoodlez]

*ressurection*

What exactly is this changing the voltage of? *fsbvtt?*

I know what vtt does, but what does FSBVTT do? (besides "stabilize high fsb's" )

[sin0822]

its just stabalizes at higher fsb liek you said, really needed for over 300fsb.

[dippyskoodlez]

its just stabalizes at higher fsb liek you said, really needed for over 300fsb.

i know that... i wanna know what voltages it changes...

[sin0822]

in ugur it changes vtt fsb, it might be gmch in bios

[zillaoc]

Thank YOU!!!!!!!!!!!!!! I am Doing this mod tonite when i get home!!!!!

heres a quick screeny with out any mods... just alot of water cooling and 2 4in air conditioner pipes. 1 for rads 1 straight into the case "yes thier all filtered... for no water to get by...

Thanx again m8!!!!