I may not have this right. I think crystal oscillators were mostly replaced by PLL chips. They're a lot cheaper. Phase Lock Loop circuits are self-regulated and put out a calibrated frequency. This comes in handy for clock chips! Which is what Sohryu Asuka Langley is referring to.
It's not surprising that your proprietary mainboard's Bios isn't replete with overclocking features. Dell, Compaq, HP, Gateway and their ilk want to indoctrinate you with their concept of an upgrade. Throw your present PC into the garbage---buy a brand new one from us!
Crystal oscillators are a lot easier to spot on circuit boards than PLL clock chips. Such is progress. It may be too much trouble to OC your PC. That's the ugly truth. Next time, buy a PC from a local VAR, aka Mom and Pa's PC store. They'll build it exactly to your specifications, if you so desire. The beauty of eschewing OEM boxen is that Mom and Pa use Standard Components. This means that you can upgrade the machine with...Standard Components.