June 15, 2016
Bad news for everyone who still uses 65-nm intel cpu based on conroe arch (for example MP1,1/2,1).
SSE4 is being used now in system application and these cpus a missing it.
For example, trying to run macOS 10.12 on MP1,1/MP2,1 will give a panic because launchd process (init process, if it dies – kernel in panic) dies with signal 4 (illegal instruction).
Your only hope is when 10.12 released and sources code for kernel becomes available, if somebody will implement sse4,1 emulator (similar to sse3 emulation in the past)