View Full Version : I can't run at 166 FSB why?

04-21-03, 11:50 PM
I can't run my rig at 166 mhz FSB with a 2100+xp-TB on MSI KT3 Ultra with 512mb of Mushkin 333 mhz stick. it's now running at 133 FSB, the other day i moved the FSB to 166 and i got a black screen after rebooting and so i put the FSB back to 133 but shouldn't i be able to run at 166?, what am i doing wrong or what am i not doing right, the CPU,mobo and memory support 166 FSB
what am i missing? can anyone point me in the right direction please, i thought it would be running at 166 by default but what do i know?

************************************************** **4/23
Hello again , thanx for the prompt replys and yes you all guessed right i've never OC'd before so all your suggestions are 50/50 some i understand others ??? still learning, but i checked my BIOS again and this are my settings.
Spread Spectrum @ +0.25, CPU FSB 133(duh),CPU Ratio@ AUTO, CPU Vcore AUTO, DDR Vcore AUTO. can you tell me how or where i can obtain info on setting the FSB to 166 without major CPU surgery.

Any and all reply is apreciated very much


04-22-03, 05:12 AM
First of all, hi all!! new here ;)

Second and the important part....

What you're probably doing wrong is running your cpu at 166 fsb, instead of just the memory... your cpu DOES NOT SUPPORT 166 fsb, however you could downgrade your cpu multplier so that would not really be overclocking your cpu, to something around 10,5... that would give around 1740, which is almost your cpus default.... (since you have a KT333 board you'll have to unlock your cpu).....

the safest run is to bump you memory to 166 and leave the cpu at 133....

hope it helps.....

04-22-03, 06:43 AM
As was said above, set the memory at HCLK+33 and leave the FSB at 133. Ill look around to see if I can get any other info for you, maybe you need to raise the core voltage if using the FSB at 166?

04-22-03, 09:12 AM
I've got the same CPU and it seems to run fine at 166 FSB (on my A7N8X). I had to bump the Vcore up by .1V for it to be stable with the default multiplier...which raised my core temperature by about 5 degrees C.

I'd agree with MatiasZ[OC] and say to try lowering your multiplier to 10.5 or 11, or even maybe 12 (mine runs fine on stock voltage at 12x166).

If you've got good cooling you can try the Vcore adjustment and the default multiplier, otherwise I'd recommend sticking with just changing the multipliers.


04-22-03, 10:24 AM
The only way you're going to get that CPU to run at a higher FSB is to unlock the multiplier. And the only way you'll be able to do that (aside from buying an nForce2) is to get one of those unlocking kits available online - a risky proposition, especially since it sounds like you've never overclocked before.

Your processor runs at 1730 MHz (133x13). Simply changing your fsb to 166 yields 2158 MHz. 99.999% of the time that ain't going to work without some sort of physical modification to the CPU and/or motherboard.

If you don't unlock the processor, the highest fsb you'll probably be able to achieve will be somewhere in the 140-145 range.

04-24-03, 11:39 PM
The ThoroughBred is not locked,It is up to the motherboard if it will show them.On my A7V333 I had 5 to 12.5 and on my A7N8X-Deluxe2.0 I had the upper and lower multiplers.But on some of the lower versions of the A7N8X-D it needed a Bios update to get them to work.