ATI 4850/4870 voltmod thread

[dejanh]

I know your cooling is better on paper, but in reality if you did not mount it properly or are not cooling a component properly then you will get overheating with an aftermarket cooler. I told you my example of VF1000. It is better at keeping the core temps down, but it sucks at cooling the VRM so my card was causing problems and I was getting diagnostic lights turning on. This is on my 4870 XOC. You are definitely overheating somewhere, question is where...

[stangracin2]

should i chop stock heatsing and use that

[LuxZg]

You could do that, but remember - in that case there is no going back with warranty (except if you can get extra heatsink somewhere). But that is a pretty good solution for 4850's. You should also try pointing one fan at VRM's in the back..

[stangracin2]

i got mine at bestbuy there to stupid to check for that

[SNiiPE_DoGG]

what is the XOC bios unlocked to in CCC? if its higher then 900 then ill flash it

[stangracin2]

[QUOTE=LuxZg;3180498]You could do that, but remember - in that case there is no going back with warranty (except if you can get extra heatsink somewhere). But that is a pretty good solution for 4850's.[QUOTE]

the light comes on as soon as i turn on the system and stays on

You should also try pointing one fan at VRM's in the back

can you post a pic of this

[dejanh]

what is the XOC bios unlocked to in CCC? if its higher then 900 then ill flash it

990/1200

the light comes on as soon as i turn on the system and stays on

You really might want to put your stock heatsink on and see what happens. If your card is still doing the same thing I'd suggest you go to BB and get it replaced before you screw it up to a point that you cannot return it.

[stangracin2]

i am

[dejanh]

Well, with a bit of tweaking now I managed to get my XOC to 855/1175 and it appears to be more or less stable. I tweaked the volts a bit to give the core 1.344V at load, and memory to 1.609V at load. However, the problem still remains where if I turn up the voltage past about 1.37V I get more and more artifacts in ATITool. The opposite of what should happen I do not even have to up the clocks, just the voltage, particularly on the core. Memory voltage seems to do the same thing but to a lesser extent. I did not really check the effect of memory voltage in detail.

[mth91]

My temps on my vram go to 90c, that is if the 3rd temp in gpu-z is vram. The second temp is going up to 103c on load. This, I believe, is the vrm's. This is all with the voltage at 1.32v.

[dejanh]

Ok, well, I am sort of leaning now that despite the reported temps it is the cooling on the VRM modules that causes the cards to fail at higher volts. I was benching/stress testing with Crysis and I noticed that with the fan at 90%-100% I can get stable 875/1185 but only if I am running the fans so high. Drop the fans to say 50% and the test freezes. The volts needed for that clock are ending up to be 1.45V core and about 1.64V memory. Either way, I am pretty much convinced now that the 4870 XOC BE does not clock any higher than say 835/1150 on stock volts. Indeed, to be generally stable you need not go past 825/1125. Pretty lousy if you ask me for a card that states should be able to OC to 950/1200.

Yeah, maybe you can do 950/1200 with LN2 and about 1.6V on the core and another 1.7 on the memory. With air-cooling the best one can hope for that is true rock-solid stability (no ATITool artifacts, any game continuous 24/7) is about 850/1150 with roughly 1.35V core and 1.6V memory. Of course, as you can tell volt mods are required. Damn lying Diamond. They may have as well put 2000MHz max core speed and 4000MHz max memory, it would be just as realistic as the current CCC OverDrive limits for the 4870 XOC BE.

I now officially give the (3rd) 4870 XOC BE I tried and the whole line a big fat

Oh and for Diamond and their lousy lying.

[mth91]

http://www.overclock.net/ati-cooling...emp-issue.html

Refer to that if you want to help me deal with my 103c temps.

[dejanh]

This is a pretty bad setup you have. For starters, you really may want to try remounting all of your sinks. Second, if you can have them copper then go with copper. I found that (on the 4870) the aluminum sinks on VRM do a terrible job cooling the VRM modules. For memory they are a bit better, but only because with a VF1000 in my case I had the cooler fan blowing down on them. Third, lose all of those fans. If you want to have a fan blowing air across your VRM, you should place it at 90deg to your card, directed to blow air out the back of your case from the back of the card (so the air flows across the card and out the back of the case). Oh and, temps #2 and #3 in GPU-Z are VRM and memory respectively.

[mth91]

They're not vrm and memory by the way. I thought that too for a long time, but it turns out that temp 2 and 3 are just temperature sensors on different parts of the core. By the way, I undid that setup, so now that big fan is just on the case side, and the little fan is gone. It just puts a little more air in there now.

The reason that I know that those temps are the core, are first of all, I heard it from a guy who knows these things, and second, if you look around, you'll find people watercooling this card, and their gpu temp #2 and #3 is very low even though they just have some heatsinks on the vrm's and memory, just like I do, without any fans even.

[Barr3l Rid3r]

They're not vrm and memory by the way. I thought that too for a long time, but it turns out that temp 2 and 3 are just temperature sensors on different parts of the core. By the way, I undid that setup, so now that big fan is just on the case side, and the little fan is gone. It just puts a little more air in there now.

The reason that I know that those temps are the core, are first of all, I heard it from a guy who knows these things, and second, if you look around, you'll find people watercooling this card, and their gpu temp #2 and #3 is very low even though they just have some heatsinks on the vrm's and memory, just like I do, without any fans even.

I'm not even watercooling but has a VF1000 modded w/ 2 fans and all mine 3 temps are low... even before I put some sinks on VRM... @ 850Mhz and got 40/50/45ºC 1.33V

[sandwichamwin]

The reason that I know that those temps are the core, are first of all, I heard it from a guy who knows these things, and second, if you look around, you'll find people watercooling this card, and their gpu temp #2 and #3 is very low even though they just have some heatsinks on the vrm's and memory, just like I do, without any fans even.

Yep, I'm watercooled and my temps are 31, 34 and 32 respectively.


And you don't need LN2 for 950mhz... Mine do that on only water.

[purecain]

950mhz is a right achievement... you got lucky there my friend....

[dejanh]

@purecain - lol, damn right...well said

@sandwichamwin - I'd really wonder about the stability of those clocks. Either you have a golden card, or you are not exactly stable but think you are...how long if at all can you run ATITool artifact free and FurMark?

I'm not even watercooling but has a VF1000 modded w/ 2 fans and all mine 3 temps are low... even before I put some sinks on VRM... @ 850Mhz and got 40/50/45ºC 1.33V

You my friend have a 4850. I'm sure it can be cooled with a VF1000 adequately. 4870, I think not. I tried, believe me.

They're not vrm and memory by the way. I thought that too for a long time, but it turns out that temp 2 and 3 are just temperature sensors on different parts of the core. By the way, I undid that setup, so now that big fan is just on the case side, and the little fan is gone. It just puts a little more air in there now.

The reason that I know that those temps are the core, are first of all, I heard it from a guy who knows these things, and second, if you look around, you'll find people watercooling this card, and their gpu temp #2 and #3 is very low even though they just have some heatsinks on the vrm's and memory, just like I do, without any fans even.

Well, I tried to share what I thought was a little bit of useful information. I am not convinced that temps 2/3 are not VRM and memory respectively, and I would differ with your friend. However, I also do not have an external temperature sensor to test this myself, so I cannot really prove it. Having said that, unless you have a defective core it is not possible that the core has 50C in one area and 75C in another. What you are saying quite frankly does not make sense, but w/e. Finally, you could simply have a faulty card or your cooler may just be completely inadequate.

[Caveman787]

dejanh he has a 4850 just look at his sig. , also people have been getting 850 on stock cooler. This cooler should perform better especially with 2 fans so I don't see how 850 can't be seemingly possible to you. Either you got a lemon overclocker or your cooler is messed up.

[dejanh]

dejanh he has a 4850 just look at his sig. , also people have been getting 850 on stock cooler. This cooler should perform better especially with 2 fans so I don't see how 850 can't be seemingly possible to you. Either you got a lemon overclocker or your cooler is messed up.

Ok, I am going to eat my own words here. Temps #2/#3 are not VRM, they are something else. I just cross-referenced them with Everest that reports VRM temps and this temp is completely different from the temps #1/#2/#3 reported in GPU-Z. It is kind of weird that they would be three core temps though, especially since they can be significantly different at times, at least for me. Now, I have a 4870, not a 4850 so you can disregard my advice if you want, but I really think that there is an issue with your cooler. If not then the card has some problems. I think though that the advice I have given you on fan positioning still stands.

[Caveman787]

I think there's most likely sensor's at different part's of the card. However, where I don't have a clue. Or it could be like the 45nm intel cpu issue with a bum temp sensor, to be on the safe side I'd reinstall your cooler, maybe add some better thermal paste.

[JeffLo]

hello guys

question what after market air cooler would you recommend for 4870 cf?

thanks

[Caveman787]

I'd wait and see how the T Rad2 comes out and see if you can fit fans on that.

Accelero s1 rev2 's fanless or gfxchilla because it can fit in crossfire I believe, otherwise dunno what would fit.

JeffLo I think I may kill you for your computer lol and why get 4870 crossfire if you've already got gtx280?

Razr, I know that but but so far the gain from going crossfire or sli seems to be 50% or so and doesn't seem worth the cost to me specialy when you could overclock the gtx280 and get 17% more performance free.

[Razrback16]

Cuz 4870 xfire is faster.

[gurusan]

after rubbing off my pencil off my 4850 and running at 700mhz stock volts for awhile I redid the pencil mod for 1.05v idle 1.35v load....and am now stable for my 24/7 clock of 820/1150mhz