I recently upgraded from a 3600+ to a 5400+ on an Abit AX78 motherboard. I just got it up and running a 5 hours ago and have been letting it idle and just updated drivers and bios. A few minutes ago I decided to try and over clock it. I wanted to start with a modest OC of 200mhz, so I set the multiplier to 14 x 220 = 3.08ghz from the stock 2.8ghz at the stock 1.32 voltage. I lowered the HT multiplier to X4 also. When I exited the bios and restarted my PC hit me with this message "warning!!! Cpu frequency has been over running. Change settings in CMOS and save Press F1 to continue or press DEL to enter setup". I pressed F1 to check my temperatures and to see if it was actually unstable. To my dismay CPUZ and Everest report my CPU back at stock speeds and and multiplier settings. The HT multiplier stayed though. I've gone through and tried various settings in the bios including a 1mhz OC and still get the same thing. So I tried to underclock it and low and behold that will work! So the conclusion I'm getting is I can not OC this proc at all. I come here seeking advice and praying I'm not right! I know its not my temps because at stock speeds I'm running 27 idle and 34 load (water cooled).
Here is my CPU info according to Everest:
CPU TypeDualCore AMD Athlon 64 X2, 2800 MHz (14 x 200) 5400+