I'm interested in Voltmodding

[Champ]

I feel like now since I've seen the best from my card, I wanna try a voltmod now. I've looked at the article about doing it to a 4850, so I think I can handle it. I know a few things off top. I'm gonna need better cooling. I'm looking at the arctic cooling Accelero twin turbo. I want it to be as quite as possible. I've seen the other one, but it doesn't have any fans. It may work just as well thou, I don't know? I'm thinking I'm going to need a new bios also. I know how to change that and all. What kind of result will I gain from doing this? 4870 like performance? I also don't know how you guys are testing your new clock rates. A few pointers in the right direction would be swell.

 

[Athlon2K15]

for testing stability,you can run benchmarks such as 3dmark vantage. ive also noticed that occt has a graphics card tester in it now,ive always set my clocks i wanted and go gaming if it seems sluggish or you see artifacts exit the game and adjust the clocks

 

[rake]

FurMark 1.7 has a Stability Test which will rapidly show up any issues such as artifacts and flickering and will also plot your temperature reading on a graph.

You will not get 4870-like performance out of a 4850, due to the differences in memory. Most 4850's will have GDDR3 whereas 4870's will most likely have GDDR5 which have a huge memory bandwidth advantage over GDDR3.

If you want a quick and easy volt mod without reflashing your bios, use the 'Profile Editor' feature in RBE. Don't go above 1158 (1.158v) as it will most likely crash your RV770 chip. Remember, voltages are 'hardwired' in to the chip, so you can only specify a recognized value. The next value down would be 1120 (1.120v).

edit: Caveat - I should mention that inadvertently undervolting a CCC profile (compared to what's in the VBIOS) could result in a crash.

 

[werez]

The only HD4850 i know , that uses GDDR5 is the Gainward HD4850 GS GLH (clocked at 700 mhz) .
It`s the closest thing to a HD4870 , but it`s super rare , and really overpriced . We are looking at around 145EUR when 512 mb versions of HD4870 are priced close to 115EUR . The hd4770`s use GDDR5 , and i saw a review on a Asus HD4770 with voltage tweak clocked at 940 , the performance gain was great , but in full load the temps peaked at 98C . The cooling used was a AC L2 PRO .
So you have to buy a Zalman VF1000 to keep the temperature in the safe zone . +30 EUR . to get close to a hd4870 . now ... that is the price for a stock HD4870 .
I don`t think you will get far with the 4850 mate ...

 

[Champ]

I know I've heard about some wild gains after the mod and decent cooling. So no to 4870 like performance, but how much better would I get compared to OCing stock?

 

[Tatty_Two]

I know I've heard about some wild gains after the mod and decent cooling. So no to 4870 like performance, but how much better would I get compared to OCing stock?

If you can hit 850mhz on a HD4850 through a voltmod, your performance will exceed an HD4870, the extra 100mhz on the GPU more than makes up for the 4870's GDDR5 memory by a fair margin.

As has ben said, pay particular attention to cooling, especially the VRM's. 850mhz should be acheivable without going overboard with the volts.

 

[rake]

An average, stable OC would be in the region of 690 / 1100 which equates to about 72GB/s memory bandwidth.

 

[Champ]

So could I get a call on the cooler that provides best performance?

 

[Tatty_Two]

So could I get a call on the cooler that provides best performance?

take a look here, this should help............

http://www.overclock.net/ati/388922-guide-hd4850-aftermarket-coolers.html