ATI 4850/4870 voltmod thread

[DemonEyez]

You will need more resistance aka 150K to 200K ohm VR.

Thanx for the info! Will pickup a new 200K trimmer this week. Crysis gives me artefacts at 1200MHz and 2.12v.
really want to try less voltage :P

[alexio]

Will a 100 Ohm vRES do for the HD4870 vGPU mod? It's a 15 turn so I reckoned it should be fine.

[LuxZg]

Under load in a few games it would just Restart that was all sometimes would do it sometimes wouldn't was kind of random but new psu = solved everything

Thanks.. I hope I'll manage ti avoid it somehow. If not, well.. I'll have to voltmod by INCREASING resistance, so I have lower voltage and clocks (dooh! )

[SNiiPE_DoGG]

Will a 100 Ohm vRES do for the HD4870 vGPU mod? It's a 15 turn so I reckoned it should be fine.

but of course sounds good to me, some people have suggested soldering a 10 ohm fixed into the line before the pot to prevent any accident that may occur, i used 3 fixed 10ohm in series for mine because i prefer low matinence

[rym]

if you have a stock 4850 heatsink thats intact i want it..

Randy

[JamesBong420]

rym i have a spair 4850 sink..

also i could not resist i grabbed a 4870 as well. $274... so now i need to find a nice 2x16x pcie mobo all i have is 16x 4x.

http://www.tigerdirect.com/applicati...1&sku=D10-4870

[Laykun]

rym i have a spair 4850 sink..

also i could not resist i grabbed a 4870 as well. $274... so now i need to find a nice 2x16x pcie mobo all i have is 16x 4x.

http://www.tigerdirect.com/applicati...1&sku=D10-4870

Arg, I did the same thing. I went out and grabbed an X48 motherboard, and the difference it makes in phenomenal.

[overcrash]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load. I think it's OCP ( over-current protection ), but I'm not certain that is the case.

[G H Z]

First mod on this new card, fan now runs 100% from POST to shut-down, perfect for air benching. Now 3DMark06 stable on default VGPU @ 875/1175 (AMD GPU Clock Tool) & 900/1200 3DMark01. I plan to do some BIOS overclocking this weekend, I'll keep you posted on the results.

[binormalkilla]

If you haven't read this, you should : http://www.xtremesystems.org/forums/...d.php?t=115387

I've seen that here, but I'm at work and it seems our routers are blocking something, as I see nothing in that first thread.....I'll check it out when I get home.

[dean0]

iam going to pick up some 10ohm resistors tommorrow for 4870vgpu mod, but im not to sure which one i need, this is what they sell;
http://www.maplin.co.uk/Module.aspx?...C=SO&U=strat15
What increase in voltage will this achieve? thanks in advance

[sea_man]

so i was able to get 900/1255 stable and artifact free using pencil mods. 1.41v gpu, 2.07v memory. i really like this card.

Hi, can you post some pics and share your configuration ( Ohm measurement)

Thanks...

[RunawayPrisoner]

To get 1.41v GPU, shade the resistor in the TPU article (the resistor, not the solder dots) to around 600 - 700, then modify the BIOS to get 1.263v at load (key in 1.263v under the clock settings), and... voila.

[rym]

what resister to shade in tpu article for gpu ?a resister could be put in place instead right. Penciling is allowing more v thriugh the resister right.
remove the resister and what resister to put in its place ?

[RunawayPrisoner]

Penciling it means you are reducing its resistance. Anyway, first pencil mod here:

http://www.techpowerup.com/articles/...voltmods/151/2

[zbomb5610]

Hi, can you post some pics and share your configuration ( Ohm measurement)

Thanks...

my pics look just like the ones here (used pencil mods)

http://www.techpowerup.com/articles/...g/voltmods/151

i don't have any resistor or hard mods so no real point in putting pics of the card itself.

.6 resistance on the gpu resistor got me 1.41v load. 3.85 i believe on the memory resistor got me 2.07v load.

[Razrback16]

How much extra MHz are you boys getting out of the mem after vmodding? I'm up to 2300MHz effective and that's about as far as I can go and be stable. Worth modding the mem?

[aussie-revhead]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load.

Why does the 4850 clock so much better than a 4870 ? Are very high clocks achievable in CF too ? I have seen mention of 1ghz on the core , wouldnt two of those crush a pair of 4870's (790/9xx) ?

[alexio]

Why does the 4850 clock so much better than a 4870 ? Are very high clocks achievable in CF too ? I have seen mention of 1ghz on the core , wouldnt two of those crush a pair of 4870's (790/9xx) ?

2x HD4850 is much more powerful than 1x HD4870, but the 4850s in a pair cost a bit more. HD4850s aren't actually better than HD4870s for overclocking though. I've yet to test my second card but the first one does 870/1235 Furmark stable, so it should do mosts benches at 900MHz core. Everything is stock, but the fan runs at 100%. I haven't seen an HD4850 that benches at 900MHz with only 1.265v vGPU (stock 4870 vGPU). I'm not even talking about the DDR4940 memory The RAM needs more volts though because the card performs equal or worse above DDR4700 than it does at DDR4700.

[aussie-revhead]

OK cool , do we have software yet that can clock these cards this high with CF enabled ? What are you guys using to clock so high ? (ie CCC only goes to 790 and the evga tool didnt support two clocked cards last time I tried).

Is there a pencil mod for 4870 ? Or solder mods only ?

[alexio]

I use AMD GPU Clock Tool 9.8. It should be floating around these forums somewhere but you can also just google it. For Crossfire I would recommend flashing the BIOS' of the cards to desired clocks if you want to go beyond the CCC limit. Overclocking cards in Crossfire could in theory work using the AMD Tool.

[aussie-revhead]

I tried AMD tool but it stuffs up with second card settings , it clocks one card but doesnt like the second .

Why does clocking from 750 to 770-790 seem to make no difference or even score less (with CCC) ? I dont think Im cpu limted that badly at 4400mhz .

Is it hard to flash the cards ?

[alexio]

I tried AMD tool but it stuffs up with second card settings , it clocks one card but doesnt like the second.

You did select the 2nd device when you tried to OC the 2nd card?

Why does clocking from 750 to 770-790 seem to make no difference or even score less (with CCC) ? I dont think Im cpu limted that badly at 4400mhz.

You shouldn't be CPU limited in almost any games/settings worthwhile with a pair of those cards. Can you give me some numbers? Like Crysis at high settings or the like. It sounds odd that the cards perform worse at a higher GPU clock.

Is it hard to flash the cards ?

No, but honestly I don't really trust the RBE BIOS Editor to mod BIOS'. I do it manually in a HEX editor. Flashing is simple if you look up how to make a USB stick bootable and read a bit about the basic commands of the flashing program. You can flash cards in Windows I think, but I use DOS because it is considered safer. Just make sure you get the latest ATIFlash and check if the BIOS you are trying to flash is 128kb in size and not 64kb.

[keninishna]

I have a volt mod on my 4870, but I have a strange problem. I can bench on 850/800, and on 650/1150, but when I clock both the memory and core, the max I am stable is 800/940. VDDC is 1.307v idle and 1.363v load. I think it's OCP ( over-current protection ), but I'm not certain that is the case.

I'm having the same issue my memory goes up to 1200 with core at 750 but I can get my core up to 880 with memory at 750. but something like 860/1000 is completely unstable. I'm trying to do the memory volt mod to see if I can get some sort of stability but I'm not sure about the memory voltage reading for vddc I read 1.5 volts. I have 1.47 volts on the core now. Its wierd though I can get 880 core and 1150 memory artifact free in ati tool but drivers crash in 3dmark

[revogamer]

i can have 885/1200 for crysis and furmark and 900/1200 for 3dmark 06,05,01 and 910/1200 for 03 with 1.45v, on air (accelero s1)