990X vs 990FX

Am I correct in my understanding that the defining difference between the 990X and 990FX is the number of 16x PCIe slots supported for CROSFIRE/SLI? Or, are there other significant omissions in the 990X that might impact say a workstation?

Yup, thats the big difference between the two. For a workstation, I would probably lean 990X.

Not sure on other things, but if its a workstation, what do you really need? Certain applications primarily you'll be using?

Good, glad to know I'm reading the specs right. Welp, probably easier to enumerate that I don't need smokin' graphics for a twitch response level FPS. Lost that level of reflexes 20 years ago. However, I do some huge compiles and am looking forward to the time when I can call: # make -j9 [yada] and it is meaningful. For fun, I run handbrake, blender, stellarium, several software defined radio apps and a smidgen of Halo Combat Evolved (plenty excitement for this ol' boy).

Which brings me to the root of all this gnashing: Given the 990X is a good fit for me, as I see it I'm really only left with two choices for a new motherboard.

GIGABYTE GA-990XA-UD3
ASUS M5A99X EVO
MSI 990XA-GD55

Yes, I know there are three there but, I have not heard anything nice about MSI in quite some time so I'll just call it a place holder. Wonder if I'll hear about that?

I've read almost as much bad as good about both other boards (many of the 5 egg reviews expound reasonable cons) and I have not been able to come up w/ a metric to help me make my decision. Support, UEFI implementation? I'm sure some if not most all here have faced a similar challenge and might share.

UEFI isn't changing much, personally I see no difference.
My main question will be why you want to change your board ? If you are thinking to get BD cpu soon then maybe it's good idea but if you want to keep your P II X2 then new board won't give you much unless you are going to run SATA3 SSD in RAID or something like that. What more there are problems with unlocking cores on some boards ( almost all Gigabyte ). Probably in 1-2 months will be some new boards or at least bioses that maybe will have corrected some issues.

Yes, the UEFI spec is mature and I'm sure that both Asus and Giga.. at least attempt to follow it. My question could be taken as: who does a better job of the implementation at this point?

Why change the board? Because, at least for me, it is most usually the first step in a generational upgrade. I, like many, have finite resources with respect to disposable income and follow an incremental approach to upgrading. Others may have much deeper pockets. Once a new board is in my chassis, I can set about accumulating SATA3 drives, USB3 goodies and eventually a BD once the pipeline is full and there is a price incentive. Each step should yield a noticeable increase in my use experience benefit and hours of happy tinkering "getting it just right".

But, all this vacillation or gnashing may well be for naught at this stage Woomack, you state that unlocking is an issue with Gigabyte. I've seen other reports of this but there is also mention a firmware flash up has solved the problem. In such a case are there still issues w/ unlocking on Gigabyte after firmware upgrade? If so, Gigabyte would be removed from consideration and case closed.

The two big advantages of UEFI are more "room' the BIOS size is getting old and tight, the other is support for 2 TB+ Hard Drives. Fancier skin, more options are also advantages.
Gigabyte adopted the 2 TB+ but was last to adopt "true" UEFI.
Asus had troubles as an early adopter of UEFI, both originally and with fixes. Hopefully and apparently corrected now.
MSI seems to vary quality over different boards, do not know if they use different design teams, or design too hard to price points.
Basically you will likely find the most information and informed users among Asus, Gigabyte has the best reputation at the moment for support and returns.
MSI any given board may be very good or not so good, many people won't use anything else.
Given your question Asus should make you happiest.
I'm mildly a Gigabyte Fanboy, I'm most comfotable with their manuals and website, and finding answers. YMMV.
There are some MSI boards reputedly best to stay away from, and some must must have.
Research ..

Ive got the 990x-UD3 and its a great board. Lots of bios features and I only had to reset the bios one time from a failed OC attempt. It will just recover and tell you that your current settings prevented boot and send you into the bios to fix it. The core unlock also works fine. I unlocked a sempron 140 last night that the previous owner had no luck with.

an ssd will make you the happiest right now. whether your motherboard supports sata 6Gb or not. Crucial M4's seem to be really good. Intels also. The sandforce seem to be fast but some have issues with them.

JackNSally, good point in fact, I checked out the M4's this morning and now have one on the way. Should make: make -j5 buildworld really fly. Thanks for the course correction.

I think you should go with the GIGABYTE GA-970A-UD3 or similar if you don't care about sli/crossfire. The base differences between the chipsets are more PCIE slots on the 990FX and no eSATA ports on the 990X and 970. The 970 offers one slot for graphics upgrade, the 990X up to two slots and the 990FX up to four slots. Also note, the 970 chipset does not feature USB 3.0 on the board itself but does have two USB 3.0 ports on the I/O panel. SB, audio chipset, LAN ect is the same. I don't think uefi has been adopted by Gigabyte at least not for amd.

I've been looking at the 970 as well Skeen. Turns out the M5A97 EVO even has 2 x eSATA on the rear connector ensemble. Gonna wait until BD ships to see if there are any new offerings that the MBAs have tied to it's availability. Barring that, I prolly will get a 970. Thank you sir!