HD 3870 will not overclock?

Blazer1 · 01-10-2009, 07:15 AM

I am having trouble setting the clock speeds on an Sapphire HD3870 gddr4 gpu. It seems any amount of memory overclock causes lockups. I can take the GPU clock from 776 to 810 fine but when I adjust memory from 1126 (stock) to 1146 it locks up? The temps. never increase? The strange thing is if I use the auto-overclock utility in ATI CCC it overclocks from 776/1126 to 776/1131, a very modest over clock, but if I test it using ATI test tool it fails???? What the heck, bumping the memory from 1126 to 1131 causes it to fail??? My temps. are idle 36c load 51c-53c., the overclocking problem is not temp. related. Any suggestions?

Blazer1 · 01-10-2009, 03:10 PM

Update,...seems to be the memory that will not overclock. I was adjusting gpu and memory speed at the same time and could never get it stable. If I only adjust the gpu I can go from 776 to 870. I can get a very small memory overclock , 1126 to 1141,.... but it does not make much difference in fps. Is there something about this GDDR4 memory that prohibits overclocking?

01-10-2009, 07:15 AM	#1 (permalink)
Blazer1 Registered User Join Date: Dec 2008 Posts: 43 OS: XP	HD 3870 will not overclock? I am having trouble setting the clock speeds on an Sapphire HD3870 gddr4 gpu. It seems any amount of memory overclock causes lockups. I can take the GPU clock from 776 to 810 fine but when I adjust memory from 1126 (stock) to 1146 it locks up? The temps. never increase? The strange thing is if I use the auto-overclock utility in ATI CCC it overclocks from 776/1126 to 776/1131, a very modest over clock, but if I test it using ATI test tool it fails???? What the heck, bumping the memory from 1126 to 1131 causes it to fail??? My temps. are idle 36c load 51c-53c., the overclocking problem is not temp. related. Any suggestions?

01-10-2009, 03:10 PM	#2 (permalink)
Blazer1 Registered User Join Date: Dec 2008 Posts: 43 OS: XP	Re: HD 3870 will not overclock? Update,...seems to be the memory that will not overclock. I was adjusting gpu and memory speed at the same time and could never get it stable. If I only adjust the gpu I can go from 776 to 870. I can get a very small memory overclock , 1126 to 1141,.... but it does not make much difference in fps. Is there something about this GDDR4 memory that prohibits overclocking?