Couple Questions [New Build]

[LordHood2]

So over the next week or so, I'm going to be ordering my new computer(). I've decided on all but a couple of things.

The first one being the motherboard. Yeah I know, ordering a new computer but not being decided on the motherboard is noobish. Go ahead, say it...... But they are very similar as far as I can tell. And i'm mainly concerned with the reviews on each from people who have actually owned/used one. The two in question are:

Gigabyte GA990FX-UD3
ASUS M5A99x EVO

It will be either one of those two boards. The reasons I picked them are A: Both seem to be capable overclockers; B: Both support at least 2-way Crossfire/SLI (not that I'll be using either right off the bat); C: Both seem like a stable platform on which to build a gaming rig. I'm just looking for some opinions more or less, or some blatant flaw that I have overlooked.

Um, on a side note. I have another inquiry about my power supply. I currently have a Corsair GS600 PSU, its about 5 months old. Maybe 6. IF I'm building a new system, should I order a new power supply, or is the one I have still plenty good enough?

Thank you all for the input.

Edit:
AMD FX4100 CPU
Asus M5A99X-Evo mainboard
XFX Double-D Radeon 6870 GPU
GSkill Ripjaws 8gb DDR3 PC3 12800
Crucial M4 64gb boot drive
Segate Baracuda 500gb Storeage Drive (will be adding a 1tb in the future).

Primary use will be as a gaming rig

[Dzzope]

On the motherboards... Personally I would go Asus... gigabyte has , in my experience, totally inadequate customer service and their returns policies are rubbish.
That alone makes me stay away from them (at least for motherboards as there is so many things that can and do go wrong with them)

[LordHood2]

Thats kinda what I gathered. I've heard lots of good regarding Asus boards, particularly the M5 series, while I haven't really heard much of anything good or bad about Gigabyte. Plus, the Asus fits my budget a slight bit more. And what about power supplies?

[Dzzope]

Totally depends on what your building... a 600 watt should be enough for any single card build.. but I've no idea what the gs600 is like..

A list of parts (major components like cpu number of hdd's and graphics card) along with general usage will let those that know psu's better than me tell you if your good to go or should upgrade..

[LordHood2]

Right, i suppose I should have put that in my OP. Let me edit that..

Edit: Added the build info

[BryceBooth]

Asus boards are well built, as I'm sure Gigabytes are as well although I don't use them in my builds. Asus has great customer support, and in my experience RMA's have been quick and painless. That GS600 PSU should be sufficient for some overclocks as well, provided you don't push it too far and have adequate ventilation. For the most part, it's usually not worth the headache going a dual-card route if you aren't pushing a display over 1080p. Looks like a nice build, enjoy.