ATI 4850/4870 voltmod thread

[jason4207]

25-50 Ohms is way too low for pencil mod.

[adpr_02]

Didn't read this thread lately, but here are some things I found out: I hope they help you guys reach higher clocks:

If the VRs get too hot they shut down the card. So I used beefy sinks on them.

There are 2 extra VRs at the top of the card that aren't covered by the stock heatsink, but with the extra voltage they get hot as well and shut down the card.

The chip that we solder for the vmem mod gets HOT!!! I had huge problems with stability, and after sinking that chip, ALL the problems went away, card 100% rock stable.

Final stats:

900/1100mhz with 1.45/1.08v
40C under extreme load, 34C under idle with 30C ambient
15942 marks in 3dmark06
9057 marks in Vantage







The load was taken immediately after 6 runs of the Crysis bench maxed out, no artifacts, NO problems.

Love this card.

[CCC]

from MMouse

voltage 1.46v, temp -68C

[Theta]

Beautiful clocks there, guys. Just beautiful.

[adpr_02]

Now, what is the max SAFE voltage I should be pushing for 24/7 use? I am afraid to go higher than 1.45 even though it is running on load much much much cooler than stock at idle.

[jimmyz]

Now, what is the max SAFE voltage I should be pushing for 24/7 use? I am afraid to go higher than 1.45 even though it is running on load much much much cooler than stock at idle.

I've run mine up to 1.55 for testing.for 24/ probably under 1.5 with water.

[Miwo]

1.55v is probably fine if you have decent cooling over the VR. I've ran 1.58v on my 4850 cooled by Accelero S1 without any problems for a few hours of benching

I'd like to see what the highest artifact free clocks you can hit on water are adpr. The 4850s seem to hit a ceiling at somewhere between 925-950MHz regardless of volts or cooling. Will run 3DMark fine, but fail ATITool artifact test and Furmark at those speeds. Download Furmark if you havn't already, its pretty heavy on the card, moreso than any other benchmark app I've tested http://www.ozone3d.net/benchmarks/fur/

[Laykun]

Pictures 2 pages before: http://www.xtremesystems.org/forums/...&postcount=352

Below for the VR values.



Not sure if it has been 100% confirmed though

I can 100% confirm the VDDC mod. It works like a dream.

[adpr_02]

1.55v is probably fine if you have decent cooling over the VR. I've ran 1.58v on my 4850 cooled by Accelero S1 without any problems for a few hours of benching

I'd like to see what the highest artifact free clocks you can hit on water are adpr. The 4850s seem to hit a ceiling at somewhere between 925-950MHz regardless of volts or cooling. Will run 3DMark fine, but fail ATITool artifact test and Furmark at those speeds. Download Furmark if you havn't already, its pretty heavy on the card, moreso than any other benchmark app I've tested http://www.ozone3d.net/benchmarks/fur/

I'll probably push it more, but not now. It was too much of a headache getting to this point, even. Maybe in a few days. I'll be sure to report my results then.

I downloaded furmark, ran it, after 1 minute my videocard - I THINK shut off. my screen went black. I just reset my pc. And I thought I was 100% stable - way to burst my bubble .

[Miwo]

told you it was tough on the card
Yes your video card will shut off (black screen) if you are unstable. You might be able to catch it and ESC out before it does that if you notice artifacts......but usually shortly after it shuts off.

[adpr_02]

No. No artifacts, just shuts off. I'm guessing something is running too hot..... Damned VRs are making my heatsinks hyper hot and they have 2 120mm fans blowing on them.... the cooling for this card is killing me.

[adpr_02]

Lowered my clocks to 880/1050 for furmark..... lowered the voltage, too. now I can withstand 4 minutes before my card shuts down. I touch the VR heatsinks and they are, I would say well over 80C.... I can't have my hand on them for more than a second.

I need to get better cooling for that, everything else that I touched seems okay. What are you using to col the VR's? I have a wide heatsink on all 8 chips, but I am thinking that (If I get the balls to rip off the sink now that it's been epoxied) I'll use that whole thing for only 4 of the chips, and get another one just as big for the other 4.

I just have to pray to a few gods tonight that ripping it off won't rip off any of the chips.

[regenade]

Well I am at 730/1100 after the pencil modding with 1.26vGPU/2.11vMem.Using the stock cooler ATM with 2 X 120mm extra fans blowing on top of them as well.
Nw in rthdribl the max temnps of the GPU is arnd 80 degrees but there is GPU Temp # 2 which really goes overboard at 90 degrees. Can anyone tell what these GPU temps #1, #2, #3 are for.

A screenshot of what I am talking it about.


Also in the stock HSF it seems there is a plastic covering all around with only the core, and the mem chips , VRMs having small gap in the plastic to have contact with the metal area(anodized Al)
Since its covered with plastic isn't it affecting the heat transfer capability and spread out
Here is the pic



Seems the stock HSF is taking too much heat and its affecting the VRMs , ram too much. So which will be a better cooler, the accelero S1 rev2 or the Thermal right Hr 03 GT. These are the only coolers which I can get locally here.

Finally thanks to all for such a helping thread

[Heretic]

The HR-03 GT should be the better cooler, but the Accelero will be the better value by far.

[Hazzan]

@CCC : any picture HD 4870 with mods ...........

[Astennu]

I would not wanna use the stock HD4850 cooler with 1.26v. You are putting about 35watt extra trough that heatsink. The HD4870 are doing 1.28v under load. And that massive heatsink is getting very very hot.

So i suggest better cooling for 1.26v.

I have a VF1000 on it now. Still hot 62c load with 1.23v 775-1125. I'm gonna do the memory mod this week.

The HD4850 on 1.25v is consuming 5 watt more than the HD4870 on 1.28-1.29. So that GDDR 5 uses 10-20 watt less than GDDR 3.

I'm not gonna clock the core much higher because at high resolutions it will get memory bottlenecked anyway Maybe not in 3DMark but in games the faster GDDR5 is showing boosts up to 25% with HD4850 and HD4870 core both clocked at 750 MHz.

BTW power draw from 1.18v to 1.23 increased with 25 watt. Compared to stock 1.14 you have a increase of 35-40 watt. 1.25 is on par with the HD4870 stock.

[dante`afk]

i just passed through the last 10 pages, any pencilmod (pics) for 4870 for better oc :f ? would

[EXPANDER]

Single HD 4870 Default Voltage 842 / 4820 MHZ Water cooler Thermaltake AGUATANK Model.

3DMARK2006 SCORE: 17885



idle 912 MHZ GPU

[Astennu]

Nice results on that HD4870. That memory can be pushed quite high if it does not get hot. But with the stock cooling that plate get so hot you cant hold your finger on it.

[Clemmaster]

I was wondering : was is the maximum wattage the regulation chip can deliver to the GPU chip on a HD4850? I made calculations, running @ 900mhz 1.49v draws 140% more than it draws with stock freq and voltage (240% of the stock wattage)
Assuming a 120w power consumption @ stock, that would lead to 290w only for GPU, that's pretty high if you ask me

Anyway, here's what I got with accelero S1 + 120mm @ 7v :



I've also flashed the card with a bios that was supposed to solve the frequencies issue in double screen (locked in 3D mode) but it wasn't working really good though :


Anyway, that's good to see this chip can run @ 160mhz 0.98v, which would lead to a 18% consumption (<22w) which is nice for laptop

Third thing : I used to be freq limited for memory chip with stock cooler. I mentionned earlier that the pencilmod didn't improve the maximum frequency I could get out of them. I though I had crapy memory chip but here's what I get with accelero S1 and its poors ramsink :

[Miwo]

I was wondering : was is the maximum wattage the regulation chip can deliver to the GPU chip on a HD4850? I made calculations, running @ 900mhz 1.49v draws 140&#37; more than it draws with stock freq and voltage (240% of the stock wattage)
Assuming a 120w power consumption @ stock, that would lead to 290w only for GPU, that's pretty high if you ask me
[/img]

I am wondering about this too. I was under the impression that the HD4850 could only draw up to 150W: 75W(6pin) + 75W(PCIE Slot). Power consumption of a stock 4850 is already well > 75W under load, and a core @ 900 1.49v would definitely send it right over that 150W envelope, so how is it that plenty of us 4850 users are running well over without much of a problem? Can the 6pin plug actually draw more than 75W?

I'm pretty confused because 4870 users are not hitting any higher even with the extra power circuitry. Perhaps with cold, but on Air/Water we are all toting around 900~ artifact free it looks like.

Also interesting to see that your Temp 2 is a good deal higher than #1 and #3. Any idea where these probes are located? I've read that #2 may be VRM temperature , but have no clue what or where #1 and #3 may be. #1 = same as Core temperature?

[Clemmaster]

I wasn't talking about the PCI-E connector which can draw more than 75w on each 12v wire without any problem, but about the chips that deliver the wattage to the GPU

[deathman20]

So what would you guys consider the max voltage for a stock heatsink HD4850 then? I plan on putting different thermal paste on it, probably slap a 120mm fan over the area to help air flow more into my dual HD4850's I got coming but I also would like to at least do the softmod (bios voltage increase) to the card.

Would that be going over the top or is that.. the sweet spot I should be looking at for at least stock cooler.

I might get another Thermalright HR-03 GT if it fits some how on my new board. 2 cards with those... ouch thats going to take alot of space and have to see how that plays out but also depends if I can get the ram sinks off my 8800GT as well. Maybe some other coolers that would be more ideal for the space would be taken into consideration as well.

[keninishna]

I've done the vmod to my 4870 I think its working but I have no idea where to measure the vcore either in windows or with a multimeter. I just soldered 3 10 ohm resistors together and wired it up to the card. Temps aren't bad on stock cooler around 61c load with fan at 52&#37; and clocks seem pretty good with no artifacts but I haven't been able to increase clocks going from 40 to 30 ohms so I'm questioning the actual voltage. I think I'm going to try 20 ohms tonight for around 1.41? vcore.

[ymer]

I will try this when I get my 4850, thjanks