DISCLAIMER: I will not take responsibility should you damage or burn out your card.

Many of you probably have the Gecube 9550XT Extreme Edition. For RM 390 it's quite a deal, because of it's near on par, if not, greater than the 9600 Pro performance. Since revision 1.0 all the way to 2.0, we have been hearing good oc results, especially for those with Hynix 2.5ns rams. But there have been only few that have succesfully overclocked the Rev 2.1. Why? I actually have no damn idea, but what i do know, is how to overlcok it succesfully. The biggest factor on the Rev 2.1 is the unoverclockability of the core, which defaults to 432 mhz. Most of whom i have heard can only oc this to 440max, with lockups anything over it. Initially I thought of a bios lock, because the 9550XT was so popular, it kept people from buying a 9600 Pro/XT. However after flashing the bios with many different versions of the 9600, I have noticed that the core remains unoverclockable, but the memory soars, so it may be a good idea to keep a 9600 Pro bios on it, more on that later.

Alas, with help of rx8, a relatively new member to this forum, we have found out where to volt mod the core and the memory.

The voltage regulator chip is an ON 1571. It's brand name was not written on it, so it took forever to find results on google and the datasheet, but after page 25 or so on google, I found it. The other problem was finding the memory voltage. It was easy to find the core voltage, which is the pin of the coil for the core. However, for the memory, the coil was rated at 1.92v. Pretty strange for DDR memory? Yes, I agree, and I personally doubt it's got gDDR3 on it, and unfortunately, I can't find out either, since I have ramsinks superglued to the mem chips. If one of you could write down the code, and post it here, I would very much appreciate it.

Alas, after simply appyling the same voltage mod on the memory as on the core (because they both have the same regulator chips, 1571), my memory was more overclockable, so I thought, what the heck, as long as it runs higher, I wasn't gonna complain. But be assured, I'm not 100% sure, that the memory mod below will actually increase mem speed, unless I know wether i got gDDR1 or gDDR3.

Ok, so I'm done talking pure, useless crap, here's the mod:
:::vGPU & vDDR Mod:::

Simply draw a pencil line at those two ] to increase coltage. Check the voltage after every pencil line though. You don't want to shoot up the volts to 2v or smth like that.

If you don't like Pencil Modding, you can simply solder a 10K Pot to Pin 7 and to the ground.

Initially my core voltage was at 1.32v and memory at 1.92 at the max OC of 435/306 to 1.71v/2.2v at 532/336. This is with stock 9550 bios, not with 9600 Pro bios, so if I flash sooner or later, my mem will fly even higher.

Happy Modding,
Regards,
Dead__Man with help of rx8

This post has been edited by Dead__Man: Apr 11 2005, 03:34 PM

no, it doesn't increase with proper cooling trust me, i've tried everything to increase core to over 450mhz, to no avail. i've got a 60mm cpu ehatsink with a 5000rpm fan on it, and some ramsinks cut from another 60mm heatsink, so the problem was never cooling.

Ok, I failed to think of newbies to volt modding. The voltage regulator has a feedback cicrcuit, which tells it wether it should send more or less volts. If you connect this pin to the ground, less voltage wil come to the feedback circuit fooling the voltage regulator into thinking there's not enoguh voltage supplied to the chip, since some of the voltage escapes vie the pencil track to the ground.

Oh, and one more thing, DON'T do it with wires, otherwise ALL the voltage will go to the graound, makes the voltage regulator think the core is not having enough power, and will send all 3.3v to the core, instantly fraing it. You have been warned.

check the pcb board, on the front top side......it will say the rev.

This post has been edited by Dead__Man: Feb 26 2005, 02:02 AM

dude, the mod is so easy, simply draw a line between at those green ] and measure the voltage, if too high, use a rubber to rub it away, if too low, draw another line.

but if it helps, i have done the mod, it was damn easy, and so has rx8, but hasn't reported here yet.

There is no reason toi be afraid to overclock, because the wore that can happen is your pc locks up or it crashes, there will be no physical damage. However volt modding is considered dangerous, because do a mistake, your card might end up dead.

To overclock just use ATITool and click "Find Max Core" and "Find Max Mem", but do his overnight, because it takes long. Then save the settings under a new profile and set ATITool to run when windows starts and use the profile you just created. If you have problems, set the core frequecny and memory frequency down by 10mhz, just to be safe.

mine isn't, that's why I bumped to 1.7v. rx8 has stock.

if you are really, really sure of what you are doing, you can use 320 grit sandpaper between the two pins, like i did. from 1.5v shot up to 2v. rub a bit away, voila, 1.6v. much better contact due to rugher surface.

fixed, link works again

does your card have two 1571 chips i the upper left and right corners on the frontside of your card? if yes, should be possible, but it would be better if you could send me some pic of your card.

you can't check vGPU and vDDR in the bios, nor with any software, only with a multimetre (should you nto have one, don't even try this mod).

to find out your voltage, there is a coil near the 1571, i've marked it in the attached pic. simply check the backside where the connectors of the coil are soldered. that's the voltage checkpoint. (set your multimetre to 2v, put the black conenctor of the multimetre in to one of the two black wires of the molex conenctor, put the red one on to the connector of the coil).

looking at your pics, you have to connect neither of the one you chose. pin 7 adn 8 are the ones, i've marked the proper trace in bue. i've attached the pic.


Attached thumbnail(s)

probably vGPU since it's quite close to your core. measure the voltage (the coil), if it's around 1.3-1.4 then it's vGPU, it it's around 2.6-2.9 (or maybe 1.8-1.9) then it's vDDR.

he's talking about the vAGP option in the mainbaord bios. it rarely affects overclockability.

well, did you remove the graphtie line again? i once bumped up my voltage to 3v artifacts, removed the graphite line, and presto, it worked again.

(i'd like to thank arj to moving this to essential reviews and guides)

btw, the coltage regulation ic has an input of 12v. my overclocking of core seems to be limited after setting the voltage over anything than 1.6v. i believe the core might not be getting enough current (not voltage, remember two diff things here).

if i connect my psu 12v to the ic's 12v input will my core get mroe current? i'm askling mroe the absolute vmod pros or electronic experts here. would appreciate any info.

here the ic datasheet:
http://www.onsemi.com/pub/Collateral/NCP1571-D.PDF

I'd just like to hereby officially announce that I killed my card when I pumped in 1.75 volts. And no, the core or mem didn't fly, my cooler keeps them at something below 45c/35c respectively.

It was the goddamned capacitors. They were unusually hot, at about 60c-70c.

And well, during a session of Jedi Academy, they blew.

RIP GeCube 9550XT Extreme Edition Rev2.1 19.01.2005 - 21.05.2005