Or you could just flash the bios to 1.1v. The bios doesnt support OVer-volting but it Does support under-volting.
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Or you could just flash the bios to 1.1v. The bios doesnt support OVer-volting but it Does support under-volting.
Is this possible? I opened up the BIOS in NiBiTor and found an unused VID code in the tables. Assuming it was 1.1V, I selected it and flashed my BIOS, but unfortunately it didn't seem to do anything (no temp change and measured with a multimeter, Vcore remained at 1.2V). I figured since 7900GT is default 1.2V in 2D and 3D, reference design doesn't bother including the circuitry to allow other voltages to be selected in BIOS.
But maybe I did something wrong? Please help if you know how. :)
BTW, my card is an XFX 7900GT Extreme (520/1500) if it helps to know.
EDIT: Also, could soft-start cause any problems? Accoring to the PDF:
So how high could I pull FB before causing problems. What is the internal ramping reference voltage? I actually did an undervolt mod for an X800GTO previously, and ran into a problem where below a certain voltage the card would run fine if it was already running, but when the computer was shut off and restarted, the voltage regulator would not turn on until Vcore was raised to this level. My best guess was that the problem was related to soft start, which this IC had as well, but I wasn't completely sure. It wasn't too hard to work around, just lower voltage while the card was on to find the lowest undervolt, then use VID codes to permanently set that voltage and remove the resistor mod. Was kind of a pain in the butt though.Quote:
The ISL6568 also has the ability to start up into a precharged output, without causing any unnecessary disturbance. The FB pin is monitored during soft-start, and should it be higher than the equivalent internal ramping reference voltage, the output drivers hold both MOSFETs off.
To get around something like this could one pull the inverting input of the error amplifier low, as opposed to pulling the non-inverting input high?
Sorry for so many questions, and thanks to any with the knowledge and patience to read my posts and explain this stuff to me. I'm actually going to college to be an electrical engineer, but am still getting the physics, calculus, chemistry, etc. out of the way -- haven't got to any of the real interesting classes yet. :)
Can anyone help me out here... I am currently leak testing my h20 loop as I re-did the tubing layout and since I still have the vmem mod and vcore and vmem read points left to mod on the card (ill post my pics up once I am done) I just wanted to ask. Are there any vcore and vmem readpoints that are closer to the edge of the card away from the motherboard? Preferably somewhere closer to the middle of the card because I can no longer us the standard readpoint as shown in the vr-zone mod as my vcore mod is rather big (full 0.5v adjustment from stock to as high as I want)
I soldered 2 wires for the Vcore read points. Look athe Pictures of 7900GT mod thread. You will see it on the last page towards the bottom.
wow this masscool VF1-plus rocks. With the 1.5 vold mot, 2.23vmem mod and switching frequency mod i was idling 42-44 C with my zalman vf-700cu and now i idle 35-36 and my load is 49-51. My load use to be 69-71 while running atitool and other similiar programs o_0. so a 20 degree decrease -_-
Its also possible your cores cannot handle anything further. I hit walls like that on my old 7800gtx all the time. I could do 700 core + 50 delta @ 1.68v but couldnt get anything more even trying voltages up to 1.8v! I havent tested out my 7900gt, but the thing I would look into is pci-e frequency. Whats the highest you have been testing with because you would probably need to try around 120 - 125mhz.
I wouldnt recommend running PCi-freq. that high. Its been known to screw up Windows installs for quite a few people over 120ish. Its never happened to me but Im pretty sure the possibility is there. I never go over 110ish because it doesnt do anything after that for Me.Quote:
Originally Posted by coolingbug
What is the benefit (or not) of raising the PCI-E frequency? Achieve high clock but by how much usually? what are the risk? frying the card/damage mobo? Didn't AGP have a frequency but it was not recommended to touch that at all? :confused:
RE AGP OC-ing, it really depended on your board & AGP card in use. DOnt touch!?...Hmmm. I had an Abit board that allowed my hercules GF2 ULTRA to do 105Mhz AGP speed...and you could see it in the Benchies...then AGP went 4x & OC-ing AGP was no longer possible! Same card, different board & then we had 8x AGP, ....OC-ing only became possible on an ASUS P4C800E Deluxe for me, thro an ATi Radeon 9800 ULTRA, but it made the benchies run with less marks for some reason.Quote:
Originally Posted by iRoNeTiK
You might see about 10 to 15mhz over 100 on PCI-e but probably wont see any appreciable increases for it. If you go too far, you might scramble your registry/install, I know someone who did.... so be careful. :)
So what do you see for increasing below 110ish?Quote:
Originally Posted by smut
lol thanks for the info, could always do repair/checkdisk and my OS is on its own HDD so wouldnt lose anything, ill look into it more but i may or may not do it. Ill probably just go to the 1.55 vmod from 1.5 and call it good and enjoy my LONG hard work i put into this card heheQuote:
Originally Posted by Kin Hell
Yeah, just be sure to cool those Voltage Regs just to be sure! :DQuote:
Originally Posted by iRoNeTiK
Oh yah i got my vf1-plus last night and it came withheatsinks so i used those and took 2 heatsinks from my zalman vf700cu and put them on the voltage regulators. Those are the ones by the vmem measure point right? the ones where some of them been melting? If it is then those are the ones i got covered.
I should post pictures, maybe later tonight/tomorrow.
My clock speeds went up a bit higher raising the pci-freq. and a lil more stable as well. But once I hit 110 they did not go any higher so I stopped there.Quote:
Originally Posted by Kin Hell
I have a Forsa 7900GT that I have done the 1.4 penmod on and no other mods. I have though upgraded to a Zalman VF900 cooler and also put a copper heatsink on the 3 evil hot mosfets.
When I clock much above 600MHz core, I can audibly hear the GPU making squeeling sound. This reeks to me of simply taking the GPU clock too high, regardless of voltage or anything else. I have however settled on a clock of 625/800 with 50 delta, giving almost exactly 10000 in 3Dmark 05 (just an Athlon 3200+ CPU @ 10x240mem)
Does anyone else notice this sound? I hope it's not drowned out by fan noise! :confused:
The voltage regulator knows nothing of frequencies of the GPU.Quote:
Originally Posted by coolingbug
Since you hit the "wall" at 1.47V and at 1.68V it is unlikely that it is an Over Current Issue (although it would be relatively easy to replace this resistor)
The Over Voltage issue is positively influenced by increasing the frequency of the voltage regulator, but since you have tried that as well, this can almost be excluded.
Since both of your SLI boards are having this "wall" my guess would be that the frequency generator within the 7900GPU cannot produce or is inhibited to accept this frequency.
C-BUZz,
Haven't heard from you over the last week. What happened with your experiment with the external power supply?
The Squealing noise you are hearing is the Card complaining its NOT getting enough Voltage. My 7800GS card made the same noise cos my 550w True COntrol PSU was fugged on one of its rails. Check just what your PSU is pushing out on its 12v, 5v & 3.3v lines. They should all be above these values under whilst under load. Also to proove further, take off as many devices as you can, Case lights, CDROMS, Hard drives etc & then see if you can go further with the card. Anything over 3 hard drives is going to cause issues on most quality PSU's eventually. Hard drives seriously "tax" the PSU.Quote:
Originally Posted by xit
Your modded card is demanding aomewhere in the region of 110Watts alone.
I'll hope you dont have a nackered PSU, but don't hold your breath, check it out! :)
Is than an Opteron 180 you got there?Quote:
Originally Posted by coolingbug
I'd be VERY satisfied with 'only' 750 core on a core which runs 450 standard... ;)
So would i. :)
1.4Vmod netted me 650-655 on the core with the stock cooler but temps are becoming really frightning at this stage> 76C under load!! :eek:
Like others here i found that 1800 on the RAM was completly artefactfree where it gave slight artefacts prior to the mod.
Soon as my EK full cover waterblock arrives i'll be benching again.
Got 11K in 05, 23K in 03 and 37K in 01 so far.
Here's 11K for '05:
Hi t024484,Quote:
Originally Posted by t024484
I've given up & I dont want to keep hasseling you heh. Card is just dead. No signs of life whatsoever. I've tried every possible combination to power the card but no luck.
Thanks anyway for all your help on this matter.
C-BuZz
I had an accident while volt moding the D508 "B" point, and it now no longer bumps ups the voltage, is there any other points on the board (other then replacing resistors) that i can bump it up to 1.4 or 1.5 volts?
Ok i see now, just to make sure though,
in this pic
http://www.xtremesystems.org/forums/...7&d=1143538288
The lower set of points act the exact same way as the upper ones?
So i can connect the 2 yellow "B" points to the 3 "C" points to get 1.4?
and 1.5 if i include the purple points?
Yes. The lower points have the same effect as the upper points.