Overclocking HD 4850

[antespo]

I have a HIS Radeon HD 4850 512MB graphic cards and i am a little confused on my overclocking results. The stock speeds are 650core 1000memory and i use MSIafterburner to overclock. My core seems to overclock fine around 720mhz but my memory i cant even move 1mhz without it crashing my computer. I'm not really concerned about the overclocking i am just curious as to why my memory wont even move 1mhz. I looked up some hd 4850 overclocks and most of them at least got the memory to 1100mhz.

Oh and my specs are GA-Z77X-UD5H motherboard, 2500k cpu, G.SKILL Ripjaws X Series 8GB (2 x 4GB) 1600 ram, and a OCZ ModXStream Pro 600W psu so yes my graphic card is really out of date for my build i decided to wait 2 months and get a new graphic card for my birthday.

 

[_zxzxzx_]

That seems really strange! Could you describe how it crashes (BSOD, black screen?). I have a HIS Radeon HD 4850 1gb and I've been able to overclock the core to around 760MHz and mem to 1100MHz.

 

[antespo]

The whole screen gets jagged lines going down it, it take up the whole screen and its mostly white with some other colors mixed in then BSOD.

 

[mrbeanladen]

The whole screen gets jagged lines going down it, it take up the whole screen and its mostly white with some other colors mixed in then BSOD.

You overclocking your mammary chips too much they overheat and then shut down, or they don't get enough power from your selected voltage increase it a little but mainly i think it's heat.

 

[antespo]

My card runs at 75C full load with occt and my computer crashed before i even get to stress test it as soon as i go to 1001mhz my computer crashes and like i said before i did some research and most 4850 get around 1100mhz _zxzxzx_ also said he got the same card as me to 1100mhz. To tell you the truth i don't really care about overclocking my card I'm just curious as to why it crashes even 1mhz above 1000 when i have read people overclocking 4850 past that.

 

[_zxzxzx_]

I agree with mrbeanladen. I think it's either heat, voltage or power related although it is quite strange that 1MHz above the stock would cause that.