ATI 4850/4870 voltmod thread

[Jimbo Mahoney]

Just an update from me:

Powercolor 4830 now running 900Mhz on the core, up from 625 Mhz default.

1.5v hardmod, watercooling.

43'C load temps.



Wondering what to limit core voltage to - they are 55nm, right? I usually figure default voltage + 20% is pretty 'safe'. The 45nm Core2's are generally considered safe at 1.45v, so I wonder if these 55nm chips would be OK to 1.6v...

You know I want to hit 1Ghz on this cheap card, although I don't think even 1.6v would do that - I'm seeing only about 30Mhz increase now with each 50mV... so that puts me around 950Mhz @ 1.6v...

[gurusan]

I thought people were blowing their rv770s up with over 1.5ish? I dunno...I've never put mine over 1.41v and its still alive and kicking from release day

[Jimbo Mahoney]

I thought people were blowing their rv770s up with over 1.5ish? I dunno...I've never put mine over 1.41v and its still alive and kicking from release day

Hey man!

Well, I've put 1.6v through it for ***** and giggles. It managed another 30 Mhz to see 930Mhz artifact-free. It's deffo at the limit now - 30 Mhz from an additional 100mV is pretty poor.

I'm not going to use 1.6v every day -just for benches. I'm happy with 1.5v for everyday use.

[gurusan]

930mhz is impressive

[@lex]

What do you guys consider as maximum safe overclock for 24/7 mode use with simple air cooling(reference 4850, Accelero S1, small heatspreader on MOSFET)? I mean voltage/frequency numbers.
Really want to know the suggestions from experienced users.

[ceemic]

Hi guys!
Now I need some help.
The card is 4850 Golden Sample. Some dude wants to do Vmem mod.
He sent me this picture: http://ceemic.pri.ee/hardware/hd4850...850gs_vmem.jpg
The memory PWM controller is RT8105, but it's datasheet isn't available.
Has someone moded it?
If i had the card, I would come up with it, but I don't.
Can someone do some measurements? Which legs are GND and what resistance is between other legs -> GND?
My first "wild guess" would be leg 6 or 7.

Thanks!

[Blazing fire]

where is the 4870. Note that it is 7 (seven), not 5 (five). All I see is 4850.

Btw, what do I do to mod a blue PCB?

[ceemic]

Blazing fire, what's Your question specifically?

PCB color does not mather, asfar components and layout is the same.

[Blazing fire]

Sorry! My question is, where is the post showing a 4870 volt mod? Eg, post #459 or something.

[ceemic]

Blazing fire, for example my mod: http://www.xtremesystems.org/forums/...postcount=1029
Guide: http://forums.techpowerup.com/showthread.php?t=65199

[adpr_02]

Hey, got a weird problem with my vmod:

I'm running Crossfire with only one of the cards modded. I just ran Windows 7, and using Rivatuner to overclock.

I'm putting 1.3V through the gpu and trying to run it at 800mhz. Whenever I start a game, however, this resets to the stock 625mhz. What is up?

[adpr_02]

Well, that was taken care of. Nothing that flashing couldn't fix. I flashed the clocks in the bios and now it works great!

Edit: Does anybody have a bios with extra voltage for the 4850 that I could try? thanks.

[Blazing fire]

Blazing fire, for example my mod: http://www.xtremesystems.org/forums/...postcount=1029
Guide: http://forums.techpowerup.com/showthread.php?t=65199

Thanks man! That was exactly what I was looking for.



what voltages and clocks are you running at now?

Btw, my blue PCB differs slighty

[adpr_02]

Well, that was taken care of. Nothing that flashing couldn't fix. I flashed the clocks in the bios and now it works great!

Edit: Does anybody have a bios with extra voltage for the 4850 that I could try? thanks.

Damn, this problem is still not over. The bios flash gave me a lot of problems so I flashed back, and again I have my rivatuner clocks jumping back to what they are stock.....Anybody know how to stop the clocks from going back to 625 once a 3d app is started?

[Jim M0rrison]

Ok, finally done with the GPU-mod on my non-reference card!

NOTE: This is a non-reference card and do NOT follow these images unless you have the Powercolor 1GB 4870 "pcs" - version 2.

I only did the vGPU mod, as there seems to be little or no use to pushing the memory on the DDR5 cards. I haven't done any extensive testing on performance yet, but one small test. I tried running 3Dmark06 at 850MHz, with the mod at max resistance (lowering stock input res from about 15.9kOhm to 14.9kOhm). It crashed immediately. Then I lowered the resistance a bit further and I passed 3Dmark06 at 850MHz core!

Some pictures then...

Soldering points and needed trimpot:


vGPU measuring points:


And some images of my card when done. Note that its a bit messy, as I have used a non-conductive glue to insulate/help with stability:



The soldering points at FB are all very very small. They are decently cleared from each other, but they are so small here is absolutely risk of detaching one of them with the leverage of moving the attached cable. I solved this by gluing a small piece of cable (1cm or so) with the end "against" the soldering point (BEFORE soldering). After the glue dried, the soldering could be done safely, and actually a lot easier than usual, as the two connecting points were already "connected" and totally stable.

Good luck for those of you with the rev2 non-reference Powercolor "pcs" 1GB!

[roger_h99.nor]

Nice work with the soldering iron there Jim

I've GPU modded my PCS rev.1 - much easier.

Card can bench at 960/vpu 1.35.
Think I've posted this earlier, but heck, it's Christmas

[terroristone]

what are you guys using to cool the pwm and other chips, i've voltmodded my 4870's and using mcw60's im also using the stock "heatspreader" and fan. in furmark my pwm temps are 90-93 before i shut it down, and i really can't overclock the card much more than stock volts.....any suggestions?
Regards Andrew

[Jim M0rrison]

Nice work with the soldering iron there Jim

I've GPU modded my PCS rev.1 - much easier.

Card can bench at 960/vpu 1.35.
Think I've posted this earlier, but heck, it's Christmas

Thanks! Its not that the soldering points were too small to solder (did have a working microscope), but rather the dread of soldering the cable to one of them and then having a gust of wind detach the lot of it...

Yours is very clean and nice - good job! Wish I had rev1 for the clearly better quality... oh well - it was cheap at the time of purchase...

It is actually rather interesting that rev1 and rev2 are so different. 50Ohms vs 200kOhms for voltage regulation input for example

960MHz is impressive with these cards!

To terroristone: Airflow is the key and makes for bigger differences than I thought myself. I you not - I gained like 15C (as in -15C) by reversing ONE 120mm fan in my chassi, making it blow fresh air on my card instead of drawing air out.

[DemonEyez]

Hey you guys, is there a voltmod for the Palit/XpertVision HD4870 Dual Sonic 1024MB card? I'm planning to get two of these babies, and plan to voltmod them both.
I'm taking about his card:


It uses a new VRM design and has the same controller (NCP 5388) as the Gainward HD4850 GS. Earlier a few people where talking about this card and seemed anxious to see it released. Any user experience so far?

I came upon this post of Dejanh concerning the same card, but it never got resolved:

Well, I just picked up a brand new Palid HD 4870 Sonic Dual Edition and I am trying to volt mod it. The voltage seems to be determined through a VID table and is controlled by NCP5388 (http://www.onsemi.com/pub_link/Collateral/NCP5388-D.PDF). The phase controller is located on the top side of the card, but it is connected to resistors on the back side arranged in two rows. The rows have 3+4 1k Ohm resistors soldered on in the top and bottom row respectively. These look to be pullup resistors however so I have no idea how VID is determined currently. Nothing seems to match the tables. Anyway, I took the DMM and measured the voltages to be 1.245V idle and 1.263V load. And that's about as far as I got. I managed to map connections on the bottom to the pins of the NCP5388 and they map as follows (I'm using the word bridge here to indicate the small section where two connected or unconnected solder points are where resistors could be added or are already present):

Pin 2 (VID0) maps to 1st set of bridges in both rows.
Pin 3 (VID1) maps to 2nd set of bridges in both rows.
Pin 4 (VID2) maps to 3rd set of bridges in both rows.
Pin 5 (VID3) maps to 4th set of bridges in both rows.
Pin 6 (VID4) maps to 5th set of bridges in both rows.
Pin 7 (VID5) maps to 6th set of bridges in both rows.
Pin 8 (VID6) maps to 7th bridge in the lower row.
Pin 9 (VID7) maps to the complete set of bridges in the lower row.

The pics of the card from the front and from the back are attached to this post (I took these from the web as my camera sucks for closeup shots)...



Help please

[Jim M0rrison]

Hey you guys, is there a voltmod for the Palit/XpertVision HD4870 Dual Sonic 1024MB card? I'm planning to get two of these babies, and plan to voltmod them both.
...

It uses a new VRM design and has the same controller (NCP 5388) as the Gainward HD4850 GS. Earlier a few people where talking about this card and seemed anxious to see it released. Any user experience so far?

I came upon this post of Dejanh concerning the same card, but it never got resolved:
...

My Powercolor 4870 1GB "pcs" has the same controller (NCP 5388) and I just modded my card successfully. Its actually just a few posts above yours!

I measured 16kOhms between pin19 and ground and soldered a 200kOhm potentiometer between that pin and ground. This worked for me and I can now adjust the GPU voltage.

Look for the resistance to ground from the 19'th pin on the image below:


Good luck!

[DemonEyez]

My Powercolor 4870 1GB "pcs" has the same controller (NCP 5388) and I just modded my card successfully. Its actually just a few posts above yours!

I measured 16kOhms between pin19 and ground and soldered a 200kOhm potentiometer between that pin and ground. This worked for me and I can now adjust the GPU voltage.

Look for the resistance to ground from the 19'th pin on the image below:


Good luck!

Thanx mate for the quick response, that was the info I was looking for. I had a hunch that i could use the same mod as you but just wanted to be sure. I'll post my results once I have my cards delivered to me.

[gurusan]

Would it not be possible to pencil mod these particular 4870s as well?

[lycanwrath]

Hello Everyone,

I am looking for some expert help

I have managed to take my HD4850 to GPU: 680 MHz and Memory: 2360 MHz
I can't go further without volt modding my card.

I have looked at pencil vmod pics on the forums around but none have the same configuration as my card.

Can you help me out please,
Here is the backview pic of my HD4850: http://img211.imageshack.us/img211/6...cardviefn1.jpg

PS: I have also attached my BIOS file, if that can be of any help.

[largon]

lycanwrath,
Pencil the resistor marked as "R711", it's located near the PCIe power connector on the backside in your pic.

[lycanwrath]

lycanwrath,
Pencil the resistor marked as "R711", it's located near the PCIe power connector on the backside in your pic.

Cool, cool, cool, will try that
Will this be for vpgu?

And also what are the points I need to use to measure the effective voltage?