ATI 4850/4870 voltmod thread

I've got an unusual question.

I've got Chieftec 450W PSU (GPS-450AA-101A). Recommendations for 4xxx series are all the way from 400-550W, but we all know they are targeting cheapo chienese PSUs, as I'm seeing much lower total-system numbers in reviews, and people say that even 4850 CF with quad CPU draws like 350W.

So - will I be able to OC 4850 or even 4870? Not going extreme, but I thought about either pencil Vmod for 4850 (under 1.4V probably) or 4870 OCed without voltmods (I've got S1 to chill either of them a bit so temps shouldn't be problem)

Rest of the system isn't heavily loaded but still:
- 1x 250GB Seagate HDD and 1x DVDRW
- 1x 200mm case fan+2x120mm fans (on S1 and Ninja)
- 4x 1GB DDR2 800MHz (@stock)
- E4400 @ 3.2GHz

CPU is currently heaviest load, but I'd rather lower it a bit if it would alow me to get more out of GPU (if PSU is not good enough)

Like I've said, PSU is Chieftec 450W, and says:
+5V=28A, +3.3V=30A (together max 145W), +12V1=14A(168W), +12V2=15A(180W);(these three 440W max); -12W=0,5A(6W), +5Vsb=2A(8W).

So? What do you experts say? Will this PSU take E4400@3.2 + HD4850@1.4V~800MHz or 4870@stock voltage~800MHz? Depending on your answers I'll be picking my card, and means of OCing, so I hope you can help me :)

P.S. I've seen a guy on OC.uk saying good 450W PSU should be fine even for 4850 CF with Quad CPU, but seeing above calculations about 240% stock wattage scared me a bit, as that's more than 2x in CF :/ Others say 550W for single 4850.. so I'm getting confused :/

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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

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I dont think so . I used my APC power chute program to check the power draw from the UPS. With the HD 4850 at stock speeds in load , its arnd 280W (with Q6600, 3HDDs, 5-6 fans, P35 board). When I pencil modded it to 1.27 VGpu & 2.11 vMem and oced to 730/1150 speeds the consumption went to arnd 325~330W. Idle consumption is arnd 210 Watts as the bios is controlling the volts to arnd 0.99V for 2D clocks (160/500). So I guess the GPU is consuming arnd 140~160W in my case when 3D loaded at 730/1150.

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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.

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I have done some ghetto mods actually. I have removed the shroud of the stock HSF and put two 120mm fans (in next slot with zip ties) blowing air to the card. In fact putting the stock fan even with both the 120mm fans running helped some more dips in temps contrary to my air circulation thoughts.Also seems my core is requiring quite some volts....1.25~1.26 vGPU load for 730~740 Mhz stable. Is it normal ! I m seeing ppl doing 750Mhz with just bios soft voltage mod :P

I picked up some 10 ohm metal film fixed resistors @ .25w with 1% tolerance, is .25w too low of a rating for the 4870 Vddc mod if i string 3 of 'em together???


on another note: i have a REALLY good clocking 4870, at stock voltage it clocks up to 875/1100 :D :D :D im going to pick up waterblocks and full 2nd loop tomorrow for the beast, unfortunatley im still waiting for my second card on newegg RMA :(

HD 4870 voltmod article posted: http://www.techpowerup.com/articles/...g/voltmods/153

would be really cool if there would be a volunteer to add more text to these articles for less experienced readers

Ok this is making me mad i tried the pencil MOD and i shaded ON TOP of the resister like the picture shows i got a 4850 card and when i boot up the voltage under load is still 1.18.

THIS is what i looked at:

http://forums.techpowerup.com/showthread.php?t=64217

Now in bios i set to 1.263 and all i get is 1.18

So wtf am i doing wrong????

I have a 4H pencil and i put a little bit of force to cover ON TOP of that resister the BLACK area i went from one side to the other ACROSS THE TOP of the resistor.

IS THE PICTURE CORRECT???

IS IT THE SECOND RESISTOR OR BASICALLY THE MIDDLE ONE????????

what is wrong guys????

PLEASE POST ASAP AS I AM HERE NOW WAITING.

Sorry for CAPS, but i tried it three times, take card out anfd put back bootup and such.. blah blah blah.

measure the resistance across the resistor before you pencil it. also measure the gpu voltage before pencil modding
then pencil it, yes it's the one in the middle (assuming you refer to gpu voltage mod pencil), exactly where the pencil tip is pointing
after you pencil'd measure resistance again, it should be lower. if not you didnt pencil right.

if you still get the same voltage even though the resistance across the resistor changed then let me know so i can investigate myself

and dont use caps it hurts the eyes

Can someone please confirm the stock vGPU and vGDDR values on the 4870?

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Originally Posted by W1zzard

measure the resistance across the resistor before you pencil it. also measure the gpu voltage before pencil modding
then pencil it, yes it's the one in the middle (assuming you refer to gpu voltage mod pencil), exactly where the pencil tip is pointing
after you pencil'd measure resistance again, it should be lower. if not you didnt pencil right.

if you still get the same voltage even though the resistance across the resistor changed then let me know so i can investigate myself

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Ok i tried again rubbing pencil over the top of the resistor and booted up and same thing 1.18-1.19 is all i get.

I even rub it a little more then before seen some lead fall off too. lol.. i blew that off of course.

I don't get it.

I measured it at 1.868 then after pencil it measured 1.796-1.798

My volt meter has 2K setting not 20K, not sure if that matters.

My volts before are 1.18 and of course 1.18 after loading up ATI TOOL artifact for not even 1 minute.

Can anyone help??

Gurusan??? anyone???

works for me

no pencil = 1.855k 1.141V
w/ pencil = 1.441k 1.167V

Yeah sure i got lower readings too, but when i booted up and tested Volts it was still the same.

Now i was in other thread and the fella in there had similar issues.... so what he did was pencil the side of it 1-2 strokes.

I just did this about 3 min ago and it drop 1.868 to 1.665 and when i booted up and check Volts = 1.22v now instead of what i had which was 1.18 and i just ran a 3dmark 06 at 740/1100 and this time it passed no freeze up, but like we all know one is not good enough.... lol

Now i may try again 750mhz to see.

Also what happens if pencil dries up or gets blowen off.. or whatever.... will card boot... lol

I can't pencil mod mine either. I have applied and reapplied the mod to the top of the pictured resistor and It did nothing.

Could they have sprayed like lacquer something over that area to prevent mods?

I can tell somethings different though when I hear you guys say you layed down a couple of strokes and changed the resistance dramatically.

Some one recommended sanding the top of the resistor could that work? I tried the other point aswell and neither gained me anything.

What dissolves lacquer? How about pure acetone hmm. I'll post back in a while.

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Originally Posted by foch3 -USA-

I can't pencil mod mine either. I have applied and reapplied the mod to the top of the pictured resistor and It did nothing.

Could they have sprayed like lacquer something over that area to prevent mods?

I can tell somethings different though when I hear you guys say you layed down a couple of strokes and changed the resistance dramatically.

Some one recommended sanding the top of the resistor could that work? I tried the other point aswell and neither gained me anything.

What dissolves lacquer? How about pure acetone hmm. I'll post back in a while.

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I stated this in my post above yours:

Now i was in other thread and the fella in there had similar issues.... so what he did was pencil the side of it 1-2 strokes.

I wasn't comfortable with that because of the proximity to the other resistors.

Edit: I just cleaned the surface first with acetone and reapplied the pencil mod and it was a success. I am at 1.24v 3d. 775mhz gpu artifact free for now.

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Originally Posted by 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.

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All the more reason to get the memory running as fast as possible! :yepp:

@Beast: What brand do you have? can you post brand and part number? Maybe see if its similar to the others with this problem so people know to watch out for it if it is indeed an issue with a batch of them, or a 'mfg'.

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Originally Posted by SNiiPE_DoGG

is .25w too low of a rating for the 4870 Vddc mod if i string 3 of 'em together???

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I guess i have to REITERATE my QUESTION always an issue in these threads is getting people who are experienced modders dont help out some of us :D ;)


I practiced soldering on my 7800 gtx today (dead already) and I got to the point where i can solder to a contact and then when I pull it off it yanks some of the micro traces :)

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Originally Posted by 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.

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Well, I re-sinked the card with even bigger sinks. So right now I'm at 880/1050 with 16 minutes of Furmark stable. I don't think that I need more time, once I reach my final clock/setup I will run it for 1 hour:D.

http://img.photobucket.com/albums/v4.../IMG_36021.jpg

Once I get my friend to lend me his n/b heatsink I'll cover those things circled with bigger sinks as they get toasty and push more. I WILL push for 925 when I get that. But for now, I'm happy with my stable card....finally:up:.

Btw. There are 2x120mm fans blowing air at 12V on that bloody card.

hey dude, what did you use to stick those sinks on there?

Probably little glue in the corner mixed with thermal paste

Hi all it my firts time with pencil mods on a GPU ,I have a couple of questions

I have 2 Radeon 4850 and would do the 2 Pencil mod for each card with a Thermaltake Duorb on the 2 card and Zalman ramsink for ram.The probleme is I dosen't have a multimeter.

1) Can someone know how line I need to do for juste boost the voltage littil ?

2)This is for 24/7 what safe voltage I can put ?

3)I hope put the 2 card at 800MHz/1150MHz it realistic ?

Thx in advance and sorry for my english again ,I am a French QC.

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Originally Posted by WheelMan

http://img110.imageshack.us/img110/2...ore2lh9er5.jpg



*runs to get his pencil*

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Originally Posted by Clemmaster

http://clemmaster.free.fr/Hardware/H...encil_Vmem.jpg

In the Vmem area of course :D

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Originally Posted by SNiiPE_DoGG

I guess i have to REITERATE my QUESTION always an issue in these threads is getting people who are experienced modders dont help out some of us :D ;)


I practiced soldering on my 7800 gtx today (dead already) and I got to the point where i can solder to a contact and then when I pull it off it yanks some of the micro traces :)

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first don't pull it off.... second you maybe holding the heat on it too long and soaking heat into the board. pre-"tin" the leads.( melt a tiny amount of solder on to the wire) and it shouldn.t take more than three sec's for the solder joint to be formed. when the joint melts remove the heat and hold it in place until it cools.

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Originally Posted by LuxZg

I've got an unusual question.

I've got Chieftec 450W PSU (GPS-450AA-101A). Recommendations for 4xxx series are all the way from 400-550W, but we all know they are targeting cheapo chienese PSUs, as I'm seeing much lower total-system numbers in reviews, and people say that even 4850 CF with quad CPU draws like 350W.

So - will I be able to OC 4850 or even 4870? Not going extreme, but I thought about either pencil Vmod for 4850 (under 1.4V probably) or 4870 OCed without voltmods (I've got S1 to chill either of them a bit so temps shouldn't be problem)

Rest of the system isn't heavily loaded but still:
- 1x 250GB Seagate HDD and 1x DVDRW
- 1x 200mm case fan+2x120mm fans (on S1 and Ninja)
- 4x 1GB DDR2 800MHz (@stock)
- E4400 @ 3.2GHz

CPU is currently heaviest load, but I'd rather lower it a bit if it would alow me to get more out of GPU (if PSU is not good enough)

Like I've said, PSU is Chieftec 450W, and says:
+5V=28A, +3.3V=30A (together max 145W), +12V1=14A(168W), +12V2=15A(180W);(these three 440W max); -12W=0,5A(6W), +5Vsb=2A(8W).

So? What do you experts say? Will this PSU take E4400@3.2 + HD4850@1.4V~800MHz or 4870@stock voltage~800MHz? Depending on your answers I'll be picking my card, and means of OCing, so I hope you can help me :)

P.S. I've seen a guy on OC.uk saying good 450W PSU should be fine even for 4850 CF with Quad CPU, but seeing above calculations about 240% stock wattage scared me a bit, as that's more than 2x in CF :/ Others say 550W for single 4850.. so I'm getting confused :/

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I would not go 1.4v with that PSU. You are talking about increasing the power draw with more then 50 watt. From 1.19 to 1.23 gave me a increase of 25 watt. Stock is 1.14v So i guess we are talking about 230 watt or even more with 1.4v.

You need a good PSU for that. My system only is drawing 380 watt with the 1.23v. And if you have a 450 watt. That not only 12v. Maybe 300-350 = 12v wattage. And the card in 1.4v will draw 230 on the 12v only. And then you still have your cpu and stuff thats also pulling from that rail. I suggest you lower your ambition to 1.2-1.25v or buy a 600 watt + psu.

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Originally Posted by jason4207

All the more reason to get the memory running as fast as possible! :yepp:

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Yeah i'm planning on doing the mem mod. To see if i can hit 1175.

Still waiting for that HD4870 1GB or the HD4870 X2 2GB :)

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Originally Posted by Astennu

I would not go 1.4v with that PSU. You are talking about increasing the power draw with more then 50 watt. From 1.19 to 1.23 gave me a increase of 25 watt. Stock is 1.14v So i guess we are talking about 230 watt or even more with 1.4v.

You need a good PSU for that. My system only is drawing 380 watt with the 1.23v. And if you have a 450 watt. That not only 12v. Maybe 300-350 = 12v wattage. And the card in 1.4v will draw 230 on the 12v only. And then you still have your cpu and stuff thats also pulling from that rail. I suggest you lower your ambition to 1.2-1.25v or buy a 600 watt + psu.

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Ok, so I'm either stuck with BIOS mod (1.21V) or buying non-OC 4870. Though I don't get it - how could this card be pulling this much power (230W over just one 6-pin PCIe connector + PCIe slot?). And I persume my E4400 if clocked down a bit to 2.6/2.8 should be less power hungry than your 5600+ X2..
Bad thing is that for a difference to 600W PSU I'd be spending too much on this whole setup (VGA, PSU, and I still need display as I'm on 17" CRT right now :/ ) grr! Btw, how is it than they run OCed quad+4850 CF with just 335W power droaw (?)

Well if you have a good psu and the PCI connector is on a rail that can handle it its no problem. Those 3 12v wires can handle the wattage only the PSU should be able to do it. The pci 1.0 specification is rated 75 watt for the connector. So a 1.0 certified connector should at least be able to handle 75 watt. But new psu's can easily do more.

The HD4870 is pulling about 40 watt more then a HD4850. A HD4850 on 1.23v 776-1125 is pulling 5 watt more then a HD4870 on 790-1100. The HD4870 is running 1.28v.

If you go from 1.19v to 1.23v on the HD4850 you get + 25 watt. So you can make a indication of how much 1.45v will use on the HD4850.

Ive done the pencil mod on my 4850 but over 1.35v im getting random reboots when running Fur bench even as low as 700 on the core. im running a 850w Silverstone Zeus, do you think this extra voltage is pulling too much ? i dont want to buy another psu and find its the same. Is the sinlge 6pin on the 4850's enough ?


btw card is water cooled, never going above 45c and i have heatsink on the VRM's and according to GPU-z the dont go over 45c with a fan blowing on them.



*EDIT*

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Originally Posted by 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.

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both my cards do the same as yours, what temps does GPU-Z report for your vrm's ?