Need AGP/PCI lock explained

[savx]

This may sound stupid, but can any one point me to an article/thread that explain why one needs and AGP/PCI lock.

 

[Sonic587]

It boils down to this: When you overclock your FSB on boards without a PCI/AGP lock, you are effectively overclocking the I/O buses as well. Example... PCI/AGP run at 33/66Mhz at stock. If you were to OC your FSB from 200Mhz to 220Mhz, the PCI/AGP buses could be then running 42/75Mhz. Many devices freak out when their frequency changes like this, leading to nasty problems, such as total HD curruptions. I've also heard of it damaging hardware. The PCI/AGP lock fixes this problem by locking those buses at their standard speeds.

 

[savx]

Thanks for the quick to the point explanation!

Now, if you have NO devices in any of the PCI slots, an AGP/PCI lock is still desirable to stable OC?

I've running an Athlon 1800+ @ 2000Mhz+ for a while now on a A7N8X dlx v2.0 mobo w/ the AGP clock set on Auto. No problems so far. Is this becuase ASUS Auto feature works so well, or have I just been lucky?

 

[watek]

Just leave it on auto!

 

[Sonic587]

PCI/AGP lock is a must for a stable OC. Without it, you are only "safe" when running standard FSB speeds. Such as 266/333/400FSB via jumpers. You'll most likely end up with a lot of problems if you FSB OC on a board without this feature. PCI devices or not. As for your ASUS, you'll be ok if you leave this option to auto or manually set it to 66Mhz. I'd say to do the latter, just so you know what it's doing.