That depends on the motherboard and BIOS settings. Most enthusiast tier boards come with 1:1, 1:2, 2:3, 3:4, 5:6 multiplier/divider ratios (CPU/Memory) and BCLCK is the base speed and DDR3 is quad-pumped so a 1:2 effectively be 100Mhz/200Mhzx4 = 800Mhz for memory speed. The more overclocking friendly boards come with a ton of options for memory multiplier/divider. To get 2400Mhz memory speed on a Z87 board will require a multiplier of 1:6 . 100Mhz for BCLCK, 600Mhz x4 = 2400Mhz memory clock.
Ivy Bridge i5-3570K@4.0Ghz, Gigabyte Z77X-UD3H, 2x4GiB of PC3-12800, EVGA 660Ti, Corsair CX-600 and Fractal Refined R4 (W). Kentsfield Q6600@3Ghz, HD 4850 2x2GiB PC2-6400, Gigabyte EP45-DS4P, OCZ Modstream 700W, and PC-7B.