Help with motherboard combo build

I would get the AMD FX 6300 and the Asus M5A97 LE R2.0.

http://pcpartpicker.com/part/amd-cpu-fd6300wmhkbox
http://pcpartpicker.com/part/asus-motherboard-m5a97ler20

Here's another mobo, a step up from the one Eco recommended:
ASUS M5A99X EVO R2.0 AM3+ AMD 990X SATA 6Gb/s USB 3.0 ATX AMD Motherboard with UEFI BIOS
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131874
$134.99
$114.99 after $20.00 rebate card
The CPU he recommended is the one I would suggest also. Newegg has it (in his link) with $10 off promo code, so it matches Amazon's price.
SATA 6Gb/s is another way of stating SATA III. It is the newest standard for Hard Drive speed and refers to the ability to transfer or write data at a theoretical 6 Giga bits /second. Many of the new Solid State Harddrives (SSD) can hit this maximum, none of the mechanical drives can. It is back-wards compatable with SATA II and SATA I hard drives.
You didn't say anything about your old machine's hard drive nor optical drive, but if they are older PATA IDE drives they won't work with the new motherboards; you will need a new Hard drive and DVD drive.

If you can't afford an SSD (they still are expensive compared to the mechanical drives), then consider Seagate's new 3.5 inch Hybrid drive (for desktops). It combines solid state for some tasks (those most performed, such as specific programs and boot up) and mechanical disks just like a regular drive. I put one in my laptop and am quite impressed by the increased speed of boot and opening some of my frequently used programs. If I hadn't bought my new 3TB drive just before the hybrid came out I would have purchased one of them.

At first glance it looks like it will work, but that is going to depend on what the current is on the +12volt rail(s). Your biggest power draw will be the video card. Per Nvidia the minimum power is 450Watts for the entire system with a minimum of 24Amps on the +12v rail. It isn't the wattage that is most important but the current (amps) available on that +12v rail(s).
I finally found a picture of the side label and it tells me that it is Supposed to provide a total of 40amps; two +12v rails at 20amps each. This should be sufficient for your needs IF the internals are new enough that the two rails share electrical loads. In some of the older designs the rails were truly separate and if you reached 20amps on a 20amp rail, that was it; the unit would either overheat and shut down or the piece of equipment would stop working properly.

The red switch for choosing 120v or 220v tells me this is an older design without Active Power Factor Correction which automatically adjusts for the correct power (and some other things).
Some inexpensive PSUs, though rated at XXX watts, can't actually produce the advertised power once they warm up, and yes there are makers of psu's who lie about the power they produce so they can sell stuff.

I would move forward with the build, and if there are any problems when you start playing games then replace it with a quality unit. (Ask us about that tomorrow).
I'm calling it a night - have a long work weekend ahead of me starting tomorrow. I will probably be back on tomorrow evening.

Evening. I will try to respond intelligently to your questions, but I have been on my feet all day at work and then doing things around the house (chores if you will) and just now finished work stuff on my PC. I tell you this because lately my track record of accurate and thought-out answers in the evening has not been really great.
The two mother boards use different North Bridge chipsets. The NB is the part that controls most of the communication and data flow between the CPU, memory, and video ( and a few other things not controlled with the South Bridge).
The first difference, and it might never be noticable, is the the transfer rates (of data) are diff: the 97 board at 2400 and the 99x at 2600 on the FSB or Front Side Bus. This will have some effect on memory speed, though you or i will probably never notice it. BUT it also has an effect on how many PCI-Ex 2.0 lanes can be placed on the mobo, how fast they will be, and whether they can be used for multiple video cards.
The 970 chipset (M5A97 board) only places two on the board (an x16 and an x4, while the 990X (M5A99 board) allows for 3 (x16, x8, and a smaller one at x4). In practical terms this means that on the 970 board if you ran two video cards they would run at x4 speed (slowest of the 2 PCI-EX 2.0 slots) and on the 990 board they will run at X8 speeds.
IN ADDITION here's a little something else to think about: You already have an Nvidia 650Ti Boost; it will be mounted in the top most blue slot and run at full speed x16; If you wanted to add another one in order to get even better frame rates and better graphics well you can't with the 970 board as it doesn't support SLI technology: But you could add another to the 990x board. (The 970 board does support using 2-4 AMD/Radeon cards in Crossfire)
More: The M5A99x supports better surround sound allowing for more speakers, and the sound chip is ever so slightly better then the other board.

So is it worth the extra money: If you think that at anytime down the road, during the life of this PC, you might add another 650Ti card or buy two other Nvidia cards and pair them up, the answer for me would be Yes.
If you are certain that your games will be smooth and resolutions satisfactory to you with the single card, then No.

RE. Power: A couple recommendations with more then enough power for your new system:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817207013
XFX Core Edition PRO550W (P1-550S-XXB9) 550W ATX12V 2.2 & ESP12V 2.91 SLI Ready CrossFire Ready 80 PLUS BRONZE Certified Active PFC Power Supply
Made by Seasonic, one of if not the best manufactures out there.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817182262
Rosewill CAPSTONE-550-M 550W Continuous @ 50°C, Intel Haswell Ready, 80 PLUS GOLD, ATX12V v2.31 & EPS12V v2.92, SLI/CrossFire Ready, Modular Active PFC Power Supply
Made by Super Flower, they're right up there with Seasonic.
(note; 7 year warranty!)
Both of these are very dependable PSU's. An awful lot of builders look at the power of the CPU and Video GPU and buy the most powerful they can afford, then stick an inexpensive PSU in to power them: Often times this is fatal to system components. Skimping on the PSU, I think you realize, is like putting a 500hp V-8 in your car or hot rod, then buying cheap skinny tires to drive on.

Hope I haven't gone on too long. I just re-read it and I know it could have been shorter, but it's late --- I warned ya!

Long day, so a quick post.
That's a really good case with sufficient room for a Cooler Master Hyper 212 EVO, depending on clearance around and over your RAM modules: I would try running the stock cooler. If you aren't into overclocking it will keep the CPU quite cool.
My wife's FX6300 is not noticeable even under moderate gaming loads: the video card and case fans are noisier then the cpu fan. Her build is in an older Antec P180 case.

Re. the powersupplies: No, they aren't geared toward SLI. A person could probably SLI a couple 650Ti's with either, but might find themselves at the edge of the power envelope. Remember, though it is slightly exaggerated, the recommended SYSTEM power for your card is 450 W. These give you a little headroom for aging, hot day, warmed up components etc. the XFX, with its 5 year warranty, is a pretty good deal at a final price of $59.99.
The power supply, as I mentioned before, is not the place to skimp on quality.
(Just read a post where someone had built a fine computer, about $1000 or more worth of CPU, high performance Memory, SSD and mechanical HDD, one of the newer just-down-from-the-top video cards, and an advertised 800W powersupply that probably cost $25-30 [that's the clue], and wouldn't power the system in any game; from a company whose reputation for powersupplies is somewhere near rock bottom. Their's sometimes simply catch fire or blow up.).

Done for the night, talk with ya tomorrow.
P.S. That board will work fine.