The major downsides of SB600 according to user consensus are:
a) RAID errors and erratic functioning in RAID 0/1, specifically on Vista 64-bit.
b) AHCI not working properly so SATA drives nearly always are running in IDE UDMA 6 mode.
c) HDD and ODD SATA/IDE combinations on many motherboards may not function correctly or not function at all due to SB600 problems which are not remedied in the BIOS releases although could be.
d) Lower USB and HDD performances in general.
e) A clock generator bug which means it will induce erratic overclocking behaviour every 9/10 attempts and limit the processor overclock somewhat substantially with the known "poor overclockers". The cause is very likely on-die PLL's falling out of the required phase synchronization window parameters.
f) For the same reasons, poor and/or limited HT overclocking.