Need some advice on overclocking the 4850 1gb card

[huntsman]

hey i ran the auto tune but it overclocked it to 690/1188, and supposobly it should overclock to a stable state. Now im getting square pixel boxes in games, they flash every couple seconds, when i put it back to default it works fine, Now ill overclock using ati catalyst thing but what can i use to check if its stable and to make sure i wont get those flashing pixels things. Really bothers me in games and im guesing thats a sign that its not stable or something.

 

[MaDMagik]

The auto-tune in the CCC overestimates the overclock as well, especially on the memory. Download AtiTool, in CCC raise the clocks manually by lets say 10mhz at a time and use AtiTool to scan for artifacts(flashing pixels). My Sapphire 4850 512mb maxes out at 695/1060

 

[huntsman]

ok thanks i will do that.

 

[huntsman]

and you raise one at a time right first core and then memory?

 

[MaDMagik]

Thats how did it(core first than memory) but I dont think that really matters. Ive got another suggestion - go back to 690/1188 and reduce the clocks bit by bit until the artifacts are gone. Im not sure but I think its the memory that causes artifacts, so I would do this one first and core later as it can take a while for the core to fail(requires longer testing, at least it did in my case), while artifacts simply either are there or not.

 

[huntsman]

alright will do that and let you know how it goes thanks man, also ill run ati tools and furmark to check it out and see what they report after 30 min of testing with furmark and 30min testing with ati tools. but thats what i was thinking of just leaving it at 690/1188 and reducing it like you said.

 

[MaDMagik]

No problem man. Whichever way you do it Im sure you will quickly find the sweet spot. Does the card have good cooling? Mine gets rather hot at full speed.

 

[huntsman]

yeah its nice and cool around 55 on load