ATI 4850/4870 voltmod thread

Hello!
I've got now my second 4850, and first was killed by Vmod, I guess. Though I only overclocked and overvoltaged it for playing Crysis, and it was under Accelero S1, after two months of using I've got unrecoverable artifacts on screen, which, I guess, was because of memory, though I didn't make mem Vmod. Guys from seller's support replaced the card (shame on me), I've been using it for more than 4 months by now.
I want to install S1 again on new card, cause it's hot. My question is what to pay attention so the card can function properly? If I'll kill it again they won't replace it, I think.
It's ASUS 4850/512M/A - nono-ref with glaciator fansink, 3-phase power supply. Those humorists from ASUS left it with no MOSFET and memory cooling(mem is completely the same as on reference)! If I install S1, can I overcklock it on stock volts without heatsink on MOSFET? What other risks exist?
Thanks for your work, guys, and for helping noobs like me:up:

where can i find the "bios mod method" for the overdrive (700/1200) in the CCC ? I want to push away the limits, but can't find the post here!!! :D Thx

edit : all is ok now!!!! :D

As long as all new posts have vanished, I'll ask once again: is there pencil GPU Vmod for this card?
http://ceemic.pri.ee/hardware/hd4850_2/
I'm sorry for asking so many times, but I really want to make that mod.
Thanks in advance.

I posted this allready, but database loss again...
http://ceemic.pri.ee/hardware/hd4850...50_mod_pen.JPG

Thanks a lot!
Do you know, what resistance corresponds to certain voltage?

can someone help with this guy
xfx 4850? THX

shot of the back
http://img.techpowerup.org/090426/xf...-scan-back.jpg

front
http://img.techpowerup.org/090426/xf...scan-front.jpg

Scrizz, do a close-up macro from that area:
http://ceemic.pri.ee/hardware/xfx_hd4850_1.JPG
And say the markings on that chip.

PS. Please use thumbnails or links instead of these fuge pics on Your post!

Quote:

---

Originally Posted by ceemic

I posted this allready, but database loss again...
http://ceemic.pri.ee/hardware/hd4850...50_mod_pen.JPG

---

Higher resistance means lower voltage? But any definite resistance will give voltage higher than stock? I'm asking because I don't want to fry my card.

Lower resistance means higher Vcore, yes. But the correlation ins't mathematically linear probably.
Lower the resistance by 10% and see how big Vcore jump was.

Resistance-voltage correlation should go about like this:

Code:

---

vcore × [Ω orig]
──────────────────  = vcore new
    [Ω new]

---

Quote:

---

Originally Posted by largon

Resistance-voltage correlation should go about like this:

Code:

---

vcore × [Ω orig]
──────────────────  = vcore new
    [Ω new]

---

---

That would be too simple:)
From my experience such things are never linear.

Quote:

---

Originally Posted by ceemic

http://ceemic.pri.ee/hardware/hd4850...50_mod_pen.JPG

---

Left marked pad on the picture is GND?

Yes: http://ceemic.pri.ee/hardware/hd4850_2/hd4850_02g.JPG

Oh, sorry, I should have watched ALL pictures before asking.
Anyway, it's clear to me now. I'm waiting for VRM heatspreader, after I'll have it I make VM and post results.
Thanks once again.

Quote:

---

Originally Posted by ceemic

Scrizz, do a close-up macro from that area:
http://ceemic.pri.ee/hardware/xfx_hd4850_1.JPG
And say the markings on that chip.

PS. Please use thumbnails or links instead of these fuge pics on Your post!

---

Hi ceemic

I'm also interested on this voltmod for the XFX 4850 XXX, more on pencil mod than hardmod, but any of the 2 it's ok.

Here is the close-up photo.

http://img125.imageshack.us/img125/666/hpim2242.th.jpg

I hope it's ok. The marking of the chip are visible.:up:

Thanks.

Paulo

aGeoM, XFX HD4830 uses the same IC and has pretty much the same layout. Check that thread: http://www.xtremesystems.org/forums/...d.php?t=222852

Thanks, I will follow that thread. :toast:

Thx ceemic and aGeoM
I don't have a camera so...
ThX!

I have an offtopic question here. Help me, please.
How do you people think which RAM heatsink is better: from AC S1, or these copper Thermaltake?
http://www.dclstore.co.uk/images/pro...cl-c0025-l.jpg
Each has obvious pros and contras... TT is very heavy, it can unstick; it's fins are thick, space betwwen them is tight - hard to create good airflow. But it's copper. AC heatsink has a little bigger fins, they are thin; but it's Al... I don't know which to choose:shrug:

The correlation between resistance change and vcore should indeed be linear, as there are only resistances in the feedback loop, AFAIK, and resistances are linear parts.
The only thing non-linear is the resistance/turn curve of a potentiometer, which gets highly non-linear in the lower reistance regions.

Quote:

---

Originally Posted by celemine1Gig

The correlation between resistance change and vcore should indeed be linear, as there are only resistances in the feedback loop, AFAIK, and resistances are linear parts.
The only thing non-linear is the resistance/turn curve of a potentiometer, which gets highly non-linear in the lower reistance regions.

---

I've read some basic things about PWM DC-DC voltage convertors. According to simplified scheme, that resistor should be the part of voltage divider, which normalizes output voltage to compare it to internal reference voltage. In that case correlation resistance/output voltage should really be linear.

HI there ;
can any one help with this card : palit sonic non reference design ?
if possible the pencil mod for the gpu , if not just the GPU soldering mod .
http://www.xtupload.com/new/image-F8E6_4A0368B8.jpg
http://www.xtupload.com/new/image-A075_4A0368B8.jpg

Have a look at these two pics:

http://www.hs-augsburg.de/~ingmar_k/vgpu.jpeg

http://www.hs-augsburg.de/~ingmar_k/vmem.jpeg

And then give me the details.

http://www.xtupload.com/new/image-2B8F_4A055D1F.jpg
http://www.xtupload.com/new/image-60C0_4A055D1F.jpg
Thanks
Hi there i tried to write the marking but this was pretty hard since the latter are almost erased , for the VGPU image it was impossible to read the hole marking i just wrote what was possible , sorry .
The question is is pencil vGPU mod possible ?.
EDIT : after more checking the gpu chip marking in 90% : ncp 5388

A trick to make the markings visible is taking a q-tip, rubbing some white thermal paste on it and then smear that onto the chip markings. Then remove the thermal paste again, maybe using another new qtip. Now the white thermal paste should've left some residues on the chip, which should make the markings a lot clearer. ;)

And concerning the pencil mod question:
I will tell you what resistances are needed and between which pins. I won't tell you exactly where to pencil. For one, because pencils should be used for writing and not for vmodding hardware. Anyone who thinks that a pencil is perfect for influencing a feedback line and getting long-term stable results that way, should seriously rethink that.:up:

So, please check the markings again to make sure they are correct.