my cpu couldn't be o/c'd,the max FSB i've got is only 133. In bios it is detected if i've raised it, it's only have effect on DRAM clock,but it doesn't have any effect on the cpu speed,even if i set it to 200mhz, the CPU fsb detected still 133mhz. and if change my multiplier to 13x, cpu speed will be downclocked to 533mhz. so all i can do is only downclock. is there any trick to deal with this thing?pencil trick or anything,n how?

There is no FSB lock, but there may be a jumper on your motherboard that has to be changed to enable FSB speeds above 133mhz. Or there may be a setting in the BIOS. I know on one of my boards, a setting has to be changed from AUTO to USER DEFINED, then the FSB can be changed in increments, otherwise it's autodetect only What motherboard do you have? Asus A7N8X-X 1800+ @8x210mhz 512mb PC3200 Ti4200/8X 128mb WDC 60GB

my mobo is MSI K7N2 Delta-L,there are 2 jumpers that deal with cpu fsb, J10(to set CPU fsb mode,has 3 pins option:short first two pin=100 mhz short second two pin = 133 mhz ) J11(used to specify cpu fsb,has 2 pins option:shorted = 100 mhz unshorted = 133/166mhz ) so what should i do? do i have to unshort J10? (default shorted to 133mhz)

I think you need to read thru your manual. Those jumpers really don't make sense to me...where's the 200mhz/400FSB option? The good thing is it appears your CPU is unlocked. So once you get the FSB issue straightened out, you should be able to clock the CPU at 8.5 x 200 Asus A7N8X-X 1800+ @8x210mhz 512mb PC3200 Ti4200/8X 128mb WDC 60GB

Normally you DO NOT! need to mess with the J10 jumper, this is only of use if your computer hangs while overclocking, then you'd need to reset J10 to safe mode (short pins 2&3) and reboot, otherwise it should be on user mode (short pins 1&2). With the J11, your option are either open (both pins) or short (both pins), and if you are overclocking obviously you want to short (both pins). Now regarding the BIOS, you have a plethora of options in there thus allowing you more flexible overclocking and as hinted by jam, under CPU clock set your System Performance option to Manual instead of Auto. Then you will be able to raise the clock in 1mhz increments. You did say you have an Athlon XP 2000+ (Tbred) that defaults @ 133x12.5, shooting for 200mhz even with PC3200 ram is a goal you most likely will not attain but you can still see how far you can go. I'd suggest dropping your multiplier to about 10x and start raising the clock at say 3mhz increments. If instability sets in, try increasing the Vcore a notch to ease things, until you hit you clock threshold. When that happens you can then go back to the multiplier and raise it. Lastly while you're at it, ensure your FSB/DRAM ration is set to 1:1 too. -- Have a happy holiday --

well, i have already set it into "Manual", but still, just DRAM speed will be increased, but no effect on CPU speed. and jam, my manual said, to use cpu fsb 200, set j11 jumper into 133/166, and set it in BIOS to achieve 200mhz.

If you don't already have it, download CPUZ to confirm your CPU settings: http://www.cpuid.com/cpuz.php Remember, you can't just jump from 133mhz/266FSB straight to 166mhz/333FSB or 200mhz/400FSB without 1st lowering the multiplier. The 2000+ is designed to run at 1667mhz (12.5 x 133), so try either 10 x 166, or 8.5 x 200. Asus A7N8X-X 1800+ @8x210mhz 512mb PC3200 Ti4200/8X 128mb WDC 60GB