For me it's the opposite, memory clocking is sooo easy it's my mem making my cpu and mobo look silly.
Getting 9845~9875MB/s read, 51.8ns latency in Everest at my 24/7 config 8x469 (3.75GHz) with divider 5:6 with timings below. That's with ONLY 2.15v set in bios and ~2.2v real vdimm and this is DDR2-667 ram but that's not the limit either but CPU clock is prioritized and it's getting cpu limited at this config.