@jaymonkey
Thank you for all the info on the modified Gigabyte BIOS. I've been to the Tweaktown site before and seen those 3rd party BIOSes, but I was under the impression that they were mainly crude amateur stabs at loosening the operating parameters of motherboards to allow for extreme gamer/hobbyist/bitcoin overclocking. If it's just a matter of someone taking the last official Gigabyte BIOS and updating the 3rd party ROMs to current official versions, that's a much less worrisome scenario.
I realize I'm not entirely consistent with my concerns here. It makes no sense to caution against a 3rd party BIOS when I happily add all kinds of not-entirely-legit-code to my computer - boot loader (made by Russian hackers, of course), hacked kexts, DSDT, SSDT, et al. I guess I'm just auto-leery of drilling down to the base metal of the motherboard itself and tinkering with code by some creepy kid halfway around the world who may be loading Trojan spyware onto people's systems at the root level. Hard to burrow any deeper than a motherboard BIOS.
I also don't have this CSM-related reboot problem some of you guys describe, so I'm not sure what I'd gain from flashing my board to F16. Ever since I wiped my UD5H/i7-3770K system and did a virgin UEFI Yosemite install with Clover, I haven't had any issues at all with my system. With CSM disabled in BIOS, I have perfect sleep and wake, high current USB, no reboot if I plug in a charging device like an iPad/iPhone. Everything just works. I don't get a boot screen on the HD5870 but I do get one on the Intel HD4000, so if I need to watch boot messages, I just switch the monitor cable over to the internal GPU.
I'm not saying definitively that nobody should install the F16 BIOS. Everyone has different needs. I for one don't have any drives connected to the Marvell SATA ports, so that might be something that's better with F16.
And to be honest, I admit I don't really understand what CSM affects if you have UEFI boot. I thought CSM wasn't part of the equation unless you were still configured for legacy MBR boot? Someone please correct me if I'm wrong on this.
I will say this, though. God bless Hackintosh. What is this, a 5 year old motherboard? My i7-3770K is at least four gens old at this point. My GPU is an HD5870, ancient by graphics standards. And yet this system Geekbenches 17K. Cinebenches 95FPS. OpenCL, which is what's most important to me as this is my Final Cut Pro X workstation, is excellent - 42 seconds to complete the BruceX benchmark, Luxmark Scala is 1100 with both the ATI and Intel HD 4000 enabled. Handbrake encodes at 300+ FPS and never gets hotter than 80C. Math-hungry plugins like NeatVideo render in real-time. What 5 year-old Mac can claim these things? I have friends with 3 year-old Macs that plod along, crying to be put to sleep.
Ah screw it. F16? Okay fine. You people kill me.