Resistors for 8rda+ VDD mod?

[Bigjakkstaffa]

Right, ive picked up a little bag of 1000Ohm (1KOhm) resistors from a mate, however there are several different types here from what i can see, because he asked what wattage they were for. Now i aint go ta clue about this, all i know is i want a 1 KOhm resistor, so he's given me a pick and mix solution.

So can anyone tell me exactly what wattage this 1KOhm resistor is for..or something :confused:

BTW im aiming for a VDD of 1.8v

--Jakk:t

[fishybawb]

You might want to PM Bovon, he'll know about this stuff. From my (fairly distant) A-Level Physics, voltage = current * resistance, so
for 1.8v = current * 1000 ie. current = 0.0018A. Or something like that ;)

[Paco103]

And the wattage is voltage * current, so 1.8 * .0018 (didn't recheck fishybawb - it all looks right) - so that would be .00324 watts, and since most standard resisters are 1Watt rated (unless they're micro surface-mount resisters or something else special) - you should be fine.

Good luck - since I have no idea what you're trying to do the formulas are all we can help with.

[Bigjakkstaffa]

Aye i might send Bovy baby a line on this, waiting to see what CV, SS and x51 have to say first though as they have carried out the specific mod

--Jakk:t

[Bovon]

Jakk PM'd me as stated, and if I understand the formula, 176 divided by a specific ohm value = ? + 1.6 volts standard VDD = the changed VDD.

so..176 divided by 704 Ohms = 0.25 + 1.6 volts VDD = 1.85 volts increased VDD.

704 Ohms is a non standard value, so:

176 / 680 = 0.258823529 + 1.6 = 185.88 volts (680 Ohms is a 10% standard value)
176 / 698 = 0.252148997 + 1.6 = 1.85215 volts (698 Ohms is a 1% standard value)
176 / 715 = 0.246153846 + 1.6 = 184.615 volts (715 Ohms is a 2% standard value)
176 / 750 = 0.234666667 + 1.6 = 183.466 volts (750 Ohms is a 5% standard value)

I PM'd him the same info as I put here, and if anybody sees or catches a mistake, please let me know.. math never was one of my better points.

Personally, I don't believe an exact VDD of 1.85 (as Jakk has indicated) would be necessary, but if that voltage is to be set exactly at 1.85, a variable resistor will be necessary. The only measuring device I see is in the BIOS itself, and those voltages we see monitored in any BIOS is only relative, and can be as much as 10% off up or down.

[Bigjakkstaffa]

These arent really exact vltages im after, just a rough sort of 'area', i'll be hitting, with 1.85v being the max desired voltage, plus of course it will never be exact due to random fluctuation in the original VDD voltage.

Once again Bovon thanks for the assistance, i'll pick up a 680 or 1000 Ohm fixed resistor soonish, then its time to get the SMD grabbers and pluck up some courage :eek:

--Jakk:t

[comp_nut]

http://www.the12volt.com/resistors/resistors.asp

[Bovon]

Originally posted by Bigjakkstaffa
then its time to get the SMD grabbers and pluck up some courage :eek:

--Jakk:t Ummm.. thats setting yourself up for intermittent problems. IMO, a much better way would be to (maybe test first with the SMD gadgets) take the board and resistor of choice to a competent TV repair shop and have them solder the resistor to the circuit. Vibration, such as fan vibes etc. will (over time) cause those clip on attachments to not make total contact at times..this in turn would cause the system to crash because the FSB would fail.

[Bigjakkstaffa]

Im gonna glue gun the grabbers in place for a more 'permanant' solution, simply because my soldering is pretty darn terrible. Several people have used glue/SMD inclusing our own x51 and it seems to be a good solution for those of us who cant solder but want a permanant and secure mod

--Jakk:t

[Someone Stupid]

I used a 760? or 840? Ohm resistor IIRC and my VDD is 1.81 - so while it may supposed to be a certain value before hand, it does fluctuate a bit from board to board a tad as I did it to a friends and got 1.80 - though that may just be from poor contact. Make sure you have an aftermarket cooler on it Jakk, it gets toasty. My AC went out (I live in Louisiana) and the comp was on. Came home, no AC and I had left the computer running. Checked the comp, it had crashed. Rebooted, had issues, had to lower the mem/FSB down to 400-406 for it to be stable, before it would do 422 rock solid stable. Had an iceburg on it, though the ambient temps went from the low 70's to the upper 90's (not Celcius :) ).

Oh, and SMD's with glue for me as well - if I soldered it, the board would be dead. :)

[Bovon]

Originally posted by Bigjakkstaffa
Im gonna glue gun the grabbers in place for a more 'permanant' solution, simply because my soldering is pretty darn terrible.
--Jakk:t I do wish you well. Glue has nothing to do with dis-similar metals.

Have fun!

[Bigjakkstaffa]

Originally posted by Bovon
I do wish you well. Glue has nothing to do with dis-similar metals.


Thats a good thing i hope?

Now all i gotta do is prize my dads credit card away from him and buy the grabbers and im all ready to blow some $&!7 up :x

--Jakk:t

[Bigjakkstaffa]

Originally posted by Someone Stupid
Make sure you have an aftermarket cooler on it Jakk, it gets toasty...

Oh, and SMD's with glue for me as well - if I soldered it, the board would be dead. :)

Got a copper Vanteq iceberg on the NB as well as on the SB keeping things cool (well, cooler than the terribly designed stock HS at least)

Good to know on the glue, did you just use a glue gun, we've not got one on our little bag of tricks so i may have to get creative with a tube of polycement :x

--Jakk:t

[ComPooTer]

whooo go for it go!!! :)

[Bigjakkstaffa]

Before i but the grabbers (hopefully tomorrow), a question, do they need to be red and black in colour, because all the sites ive seen using SMD grabbers for the mod use a red and a black set with red and black wire in the respective grabber. Only thing is i can only order em in pairs of the same colour, so for me to get a red and black combo i'll have to buy 4 grabbers which would cost quite a bit really. Again i cant see why the colour woudl be an issue, BUT, better safe than sorry.

Cheers

--Jakk:t

[Someone Stupid]

I don't see how that would be an issue with seperate grabbers personally. Though I got a set of two from a relative, and he gave me red and black ones. It's just an extension of the wire, so it shouldn't matter. Though I'll let Bovon chime in for the final say on it. Don't want to listen to someone stupid do you? :D

[Someone Stupid]

Missed the glue comment Jakk: I used a gun, just used an some industrial hot glue since I had it available and it was easier to deal with. A cheap hobby glue should work though as I have seen a picture of someone who used that with the usual cheap fairly clear hobby glue. Don't know what x51 and CV did though.

[Bovon]

Originally posted by Bigjakkstaffa
Before i but the grabbers (hopefully tomorrow), a question, do they need to be red and black in colour. Only if the motherboard (and other parts) can actually see whats going on.

plus DC voltage is usually on the end of a red wire.. the negative voltage is black... Anything inbetween will work as long as the indivual knows which is plus and which is minus.

[Bigjakkstaffa]

Cheers fellas

--Jakk:t

[Bovon]

Originally posted by Someone Stupid
Though I'll let Bovon chime in for the final say on it. Don't want to listen to someone stupid do you? :D HEH!!

Well..my concern would be if the glue happened to get a little bit between the grabbers and the leg it is supposed to be attached to..it could create a partial (going and coming) open circuit...which would probably crash Windows, and somebody would be pulling hair trying to figure out why.

Also, dissimilar metals usually create an oxidation process and corrosion sets up between the two metals. Two different metals + some acid is the foundation for most batteries.

I can certainly understand the use of such an item... I am fair when it comes to soldering, but I don't really do much anymore.. and you tend to loose some of the expertise over time if you don't do something every day.. and I would not like to do that solder job myself after looking at the pics. Lots of times we may have a good TV repairman locally that is good at working on small boards and parts like this, and probably would stick that resistor on pretty cheap.

[Bigjakkstaffa]

Most likely the glue i will be using will be epoxy resin, will this pose any of the problems you mentioned Bovon? :confused:

Also, SS have you put Heatsinks on the MOSFETS? As soem people seem to make out thet they are vital for this mod, whiel none of the images ive actaulyl seen of the completed mod have them on

--Jakk:t

[Someone Stupid]

I really should get a digital camera. CV had asked for picks of how I managed my 120 Delta onto an SLK, that was a horrible paragraph trying to describe that. I used nickel plated BGA ramsinks I had from an old TI card that I ripped off then sanded down and attached using AS epoxy. The heatsinks didn't come up much though so I had eventually managed to get them off (freezer, saranwrap (humidity) and patience). Had access to a band saw with a metal cutting blade so I took an old Athlon heatsink and cut it up, then filed the corners to remove the rough spots and then polished them up. It could be done with a hacksaw and file, but it is a lot more work as I started with the hacksaw until I realized that with a 30 minute drive I could be doing it with ease at my parents' house and I had to get some finishing paper from my dad's shop anyhow. With the cut up block the outlet fans would actually pull some air through the Heatsinks thus provided some cooling instead of a place to store some heat before getting hotter due to being surrounded by rather tall capacitors.

If you do the BGA route you may want to get a Zalman fan bracket (or get creative), and mount a fan blowing unto them. I could fit 25x25mm fans in there (tightly) and attach with plain hobby glue to caps, just it wasn't worth the trouble looking back as I don't think they were getting suction being so close to three exhaust (2 rear, 1 PSU fan).

[Bigjakkstaffa]

Ive got a shedload of spare HS's so i'll just cut em up with a hacksaw and pop em on, ive also got a 25x25mm fan amongst my arsenal of bits and bobs, so if i can figure ot how to attach ti i may use that.

Cheers

--Jakk:t

[Someone Stupid]

If you have tall (CPU heatsinks), you won't need the 25x25 fans, or if you have only one exhaust, or two really really slow ones. But if you have a PSU fan and two decent fans in the rear, if you go with small heatsinks, I don't know if they will have enough suction (unless they are the little delta screamers) to actually force any air down. With the cut cpu block you can let the exhaust fans do all the work due to the increased height of them.

[Bigjakkstaffa]

Ive got 2x80mm sucking out at the rear upper of the case near to the mosfets and the PSU is a dual fan jobbie, with one sucking up just overhead of the mosfets and then another in the back of the PSU blowing the hot air out, so that should be enough if im using a CPU HS you think?

--Jakk:t

[Someone Stupid]

Exactly the setup I have in regards to that area. That's why the 25x25's (taken from active DDR ramsinks) I didn't think were doing anything more than blowing half their rated CFM if that onto them when using the BGA. Now it is just a sawed up heatsink block. Only one block was ever above slightly warm to the touch (but I was pulling 1.9 to 2.1 then for the vcore, 1.81 vdd, and 1.85? vdimm) and it wasn't scalding, but you knew your finger was on it for [*-deleted word-*] sure. So if your going for major pushing, at least getting it on the third IIRC mosfet is essential. At 1.75 vcore - stock 8rda+ vdimm and agp voltages and 1.81 Vdd they all are quite fine to touch.

Used an old AMD Duron block that shipped with the 1200. Relatively thick base and if sawed and positioned correctly could get 3 fins for sure out of it per MOSFET with space btw them.

I had all fins running horrizontal (=) so to speak except the top one which I stuck on a 45 degree angle ( \ ) due to the fan above it and the rear exhaust. Had to cut a bit off for the angle, but not much.

(*** Polite language only please *** - WSUA (http://www.internet.com/corporate/legal.html) 3. a.)

[Bigjakkstaffa]

I'll be hacking up an old alu coolermaster HSF offa a 1ghz tbird so it shoudl be okay to deal with it, just got to work out how best to cut it now methinks

--Jakk:t

[Bovon]

Originally posted by Bigjakkstaffa
Most likely the glue i will be using will be epoxy resin, will this pose any of the problems you mentioned Bovon? :confused:

All glues that I am aware of are insulating..and if you do not have a very good contact with the grabber when the glue is applied, some could get in between the grabber and the MOSFETS leg you are attaching to. Just try to get the grabber well situated and then apply the glue without touching or disturbing the grabber. Hopefully you will have a good connection that will hold.

Also, SS have you put Heatsinks on the MOSFETS? As soem people seem to make out thet they are vital for this mod, whiel none of the images ive actaulyl seen of the completed mod have them on

--Jakk:t

You can get some Artic Silver epoxy and glue the modded heat sink on the MOSFET.. or, you could try making your own by making some fine brass filings and mix that up with some epoxy..use all of the brass filings you can and still have the epoxy workable..put a small amount on the chip..smear a dab on the heatsink.. and let set over night or maybe 24 hours...even if the epoxy says it cures in X number of hours, it continues to cure for several days. With those grabbers inplace, you will not have much room for a heatsink.

[Bigjakkstaffa]

Aye ive got thermal epoxy paste and have added passive coolers to SB chips before so it shouldnt be too much of a worry, about the gluing of the grabbers though, could you gimme a mock up diagram or sumink of how you think it should go if possible?, as i was just gonna attach the grabbers and clag glue around em to make sure they didnt come loose, but it sounds liek a more careful method may be needed :confused:

--Jakk:t

[Someone Stupid]

Just when glueing, hold the grabbers upright and pull them towards the end of the "leg" your trying to grab. That has the most surface area for the grabbers to brush up against, and the glue dries fast enough that it shouldn't be hard to do. If you do it wrong, the comp just won't boot up - no damage done. At least my friend tried it several times before asking me to do it - he said it just wouldn't bootup. I got all the gunk off, cleaned the grabbers and did it as above and it worked fine. Just make sure you grab the right legs.

[Bigjakkstaffa]

Not to sound like a retard but, could you point out what you would class as 'the end of the leg' on this, im assuming its the point furthest from the chip itself:confused:

http://8rda.com/upload/8rda_vdd_chip_mod2.jpg

Cheers

--Jakk:t

[Bovon]

A "leg" is commonly used to describe any lead coming out of a device that will be attached to another device. A transistor has 'legs', and normally one would trim the 'legs' back some so that there will not be any excess when it is attached.

In this case (looking at the pic) you may need to attach the grabbers up close to the body (thats the black thing where you may put a heatsink) so that it will "Grab" ahold of that leg..not below where it has been soldered. You need the part of the leg (or properly...the lead) free of being soldered so the grabber will not be trying to slip free because it cannot get a good grip on the leg.

[Bigjakkstaffa]

Makes sense to me does that. The grabbers should be here tomorrow so i can actually visualise how im gonna do this thing. I'll pop back with any queries then to be sure

--Jakk:t

[causticVapor]

Jack, did you get my pm? :confused:

I was wondering, as I didn't get any reply.

Anyway, if you didn't, it's ok, and the amount of power going through the resistor is really small. After all, it's only an amplification circuit, so the base current is controlling a really large exit current.

Just in case you didn't get hte pm, here's my little diagram:

http://img.villagephotos.com/p/2003-8/339670/VDDmodwithSMDStupidGrabbers.gif

[Bigjakkstaffa]

I did get it yeah but i think i accidentally deleted it or sumink :confused:

The diagram looks good to me just a question about the 'terminating blocks' though, what are they and are they necessary? (im guessing theyre part of the grabbers themselves?)

Im gonna be ripping the wires from an old 486 fan, which uses 4 pin molex connectivity. I was just gonna pull out 1xred and 1xblack wire and use those in any order, i cant see there being a problem with that., but again if there is, i would appreciate a shout.

Also in addition to putting HS's on the mofsets would you reccoment i pop one on the VDD Regulator too, as it has been suggested in articles i've read elsewhere?

Thanks for the help thus far, im pretty confident i can pull this off now thanks to you guys, all that remains now for me to clarify is how im gonna glue this :confused:, but i reckon i'll have a clearer idea whan i actually get to see the grabbers themselves

Cheers

--Jakk:t

[causticVapor]

Those blocks are there so that you don't have to solder anything. All you have to do is screw the resistor and exposed wire ends in, and you have a completely reversible, reliable connection.

any reasonably thick wires will do.

Putting a heatsink on the VDD regulator helps cool it down but does not noticeably affect stability. I just like to use it as a safety measure.

[Bigjakkstaffa]

Right the grabbers are here and ive got the wire sorted. So all i need to do is solder the resistor to the wire, got that, however how do i connect the wire to the grabber, there is basically a little hoel at the top end of the grabber, which im asuming i should poke the stripped wire end through and possibly knot it or something to ensure it stays secure and in contact with the metal (i.e. conductive bits) of the grabber?

Hopefully get around to doing this in the next few days as my dads off work, so i can call on his expertise, which is only just a bit better than mine (and as you can probably tell i know sod all about this electronics lark :eek:).

Then connect the 'tweezers' of the grabbers to pin 1 and 4 in any order, clag some glue on to make sure its secure, add HS's to the mosfet and the VDD regulator, power up, cross fingers, and hope for the best?

Its getting exciting now :D

Cheers

--Jakk:t

[causticVapor]

The terminating blocks are there so you don't have to solder the resistor to the wire. Not a necessity, but a convenience.

You can twist the frays together and reinforce them with glue if you don't have solder, and they will work reasonably well. Best is with solder though, and as you said twisting the frays together will make soldering easier.

[Bigjakkstaffa]

Cut and polished the HS's today, hopefull get them on and the mod done friday, we've foudn the soldering iron (well, we've got an idea of where it is at least) so we're gonan solder it, chewy bit is gonna be getting the wire back up through the plastic 'cap' of the grabber and to the resistor, i dont wanna run without the cap in case of a short

--Jakk:t