I have a motherboard GA-MA785GM-US2H with a Athlon 64 X2 dual Core 4400+ 2300MHz with 3 GB Ram DDR II PC5300, I set on my BIOS CPU Host Clock Control to manual and CPU Frequency set the range to 249MHz the multiplier is the max of 11.5 on a AMD CPU. 249 X 11.5 =2863.5 I raise the CPU volt to 1.33 it is stable but on 250MHz my computer start rebooting. I will appreciate if any way I can raise to 3GHz on the BIOS with other setup because I am new on over clocking I will appreciate any help.
Change the RAM to the slowest speed, rise the FSB to 250 and try again, if you can't get stable add a little more voltage. But don't go above the recommended voltage for the CPU and keep your eyes in the temps.
What is your memory doing? Have you been adjusting the memory divider to keep your memory from being overclocked beyond it's spec? Also, you can trying dropping the multiplier on the hypertransport buss.
Beyond that, as mentioned the old X2's were really tough to go more than 2.8ghz with. If you have a stable clock at 2.8ghz, you might just want to call it good enough until you can do complete platform upgrade.
Congratulations on overclocking a 4400 (2.3GHz) to 2863Mhz! I couldn't get my 5000+ that high! But my motherboard was an OEM ECS.
As has been mentioned previously, the RAM multiplier could be limiting. Drop it to the slowest speed until you get your CPU overclock finished. Then try increasing it until it fails Memtest86+ and you can either loosen the timings to make it pass or slowing it down, then tightening the timings.
If you'd like, I can mail you my Athlon x2 5000+ (Brisbane). It'll only cost me about 3 stamps for shipping. But I'd need you to mail me back whichever CPU runs slower on final overclock. I don't mind a downgrade because it's my secondary rig that I'll probably give to my Dad. And he's running a Pentium 4 Willamette Socket 478 at 2.4GHz so anything is a huge upgrade.