Turn off C1E support and AMD CaQ before doing any overclocking.
As for the CPU Voltage...it allowed me to change it, but the change wasn't actually made, voltage was still being reported at the oem 1.375. In order to make the voltage actually change I had to adjust the first CPU Voltage setting(VDD or something like that), as well as the normal CPU Voltage. Once I had both adjusted to the same value, CPU-Z finally reported the increased voltage.
I have been unable to reach a fully stable 4.0GHz, the closest I got was with the following settings adjusted...
C1E = Off
CaQ = Off
CPU FSB = 250MHz (Default is 200MHz)
CPU Multiplier = 16x (Default is 17x)
CPU VDD = 1.4750v (Default is Auto)
CPU Voltage = 1.4750v (Default is Auto)
NB = 2000MHz (Default is 2000MHz, but adjusting the FSB increased this number to 2500MHz and created an instability so I put it back to default)
I did not adjust anything else in BIOS.
At those settings, which are well within any limits for this CPU, I was doing fine until about half an hour in to Prime95 blend testing. The PC shut itself down, fried either the PSU or the MB...or both. Had to RMA them both, still waiting on them to be delivered back to me. Still have no idea why this happened, could have been temps(max individual core temps were 65, max overall cpu temp was 61), could have just been something faulty that took a little stress testing to finally show itself.
There have been a lot of people having trouble hitting a fully stable 4.0GHz, so you may have to settle for 3.8 or 3.9. I don't know if it's the board or the CPU, haven't talked to anyone else with another-brand 890fx.
Check with another monitoring program to confirm the current voltage, which is not the VDD V.
The effective voltage is that regulated by CPU V option. Let CPU VDD V always AUTO.
I also suggest keeping the CPU-NB at 2500~2600MHz and raise the CPU-NB V to 1.20~1.25 V. This will give you a huge performance gain.
You may also overclock them only by the ratio, without touching the FSB. This way is much easier.
To overclock, you must disable the spread spectrum option. To let DDRs at their rated speed, you have to adjust your bios memory settings too.
Edited by C_Matrix - 7/6/10 at 6:24am