XP2400+ on A7N8X no longer able to use upper Multis (13+)

After using a XP 2400+ (15*133) on a A7N8X Deluxe (Rev.1004, Bios 1002A) for a month without any problems, I decided to go for some mild overclocking.

XP 2600+ (12.5*166) worked flawlessly at 35 °C under load, but from now on the upper Multis (13+) were no longer available, 15*133 and Auto resulted in 933 (7*133).

The XP (AIUGB 0244) has not been unlocked or modified, it looked normal when I bought it from a respectable retailer.

Presuming some CMOS-corruption, I cleared the CMOS while upgrading to Bios 1003: The higher Multis are still not available.

Any explanation for this strange behaviour? While I can live with the minimal overclock to a XP 2600+, I am curious what caused it. There were no hardware changes, just BIOS-settings, the CPU was never removed from the motherboard.


no exotic hardware, stable system:

XP 2400+ AIUGB 0244
A7N8X Deluxe Rev.1004, Bios 1002A and 1003
375W power supply, voltage ok
2*512 Infineon PC 333
ATI/HIS 9700 PRO

seems your chip was unlocked due to the BIOS Flash
That is really good. I had to mod my socket to make my CPU unlock.

Are you saying you upgraded to a 2600? If so, I believe your problem is that the xp2400 is a 133fsb chip that uses the upper mutlies, where you would get lower multies with a xp2600 166fsb chip. Nothing to do with the bios flash, just the way the cpus are.

Jim

I seem to have been unclear. Sorry.

It is one chip (a XP2400+). After overclocking it to XP2600+ levels (12.5*166 instead of 15*133), it was no longer able to run at the higher Multis(13+), even at 133. Setting the BIOS to 15*133 or AUTO results in 7*133, while setting it to 12.5*166 works fine.

This seems strange.

What bios revision did you start having this problem with? I started having problems as soon as I went to 1003. I'm going back to 1002a or uber bios.

Edit* just flashed back to 1002a and all my problems are gone, with 1003 i would get stuck into a reboot loop right before it loaded to the desktop. Only way it it would run is with everything set to auto, now back upto 205fsb.

Why would you want the higher multipliers anyway? Your best overclock is with max cpu speed AND max fsb.

Thanks for Your response.

@ Weasel

The board had the unreliable 1001G Bios when I bought it. I immediately flashed to 1002A, and it worked just fine at auto (15*133). I switched to 12.5*166 while still using 1002A, but I lost the upper Multis. Flashing to 1003 did not help. I have not yet tried the Über-Bios.

@ TC

System runs 12.5*166 stable at a low temp without overvolting. 13-14*166 should be possible. RAM is fine at 166(2-2-5-2), but I have to slow it down at 180-190. This board seems not able to reach 200 without modding.
So I can either buy new RAM and/or modify the board to go for 200, or just increase the Multi -if possible- and stay at 166. I am sceptical about the frequencies between 166 and 200, as they are no multiple of 33 (PCI, AGP).

Just set the agp frequency to 66, it will lock the agp/pci at 66/33, no matter what the fsb is at.

I've had two boards and both will do 200 with a simple fan added to the northbridge passive heatsink. Going above 200 is where mods are usually required. You can lock your pci and agp bus so the higher speeds are not a problem. Really the only serious concern is having ram that is up to the task.