Beginner build questions and Micro Center vs online, warranties, shipping, etc. cons and pros?

At Microcenter's website, select your local store location, then add the FX-8320E and GA-78LMT-USB3 to your cart.

Price should be $120 with tax. That's the CPU+MOBO combo deal to get from MC right now if you're building a budget AMD box.

The GA-78LMT-USB3 is a microATX board, and is both better quality and less expensive than the ASRock 970 Extreme3. Furthermore, it's the same size as the board in your p6310y, so you can save yourself the cost of a new case and just put it in there instead.

The 760G chipset on the GA-78LMT-USB3 comes with a very basic GPU builti-in that can be used for office applications and web browsing reasonably well, but should be replaced with something if you want to play any games.

When buying a GPU to use for light gaming, there are thresholds where your dollars are paying mostly for the packaging and materials and stocking/distribution/advertisement etc. Most GPU's sold for less than $100 begin to quickly fall into this category, but not all. Unfortunately, If you are trying to get the most for your budget, I can not advise buying your GPU from microcenter as their prices on GPU's are bordering on non-competitive, especially when you factor in local Tax. They have a MSI Radeon R7 260X for $130+tax, which is the best "deal" in lower end GPU's that they have going right now (260X's and 750Ti's can be ordered elsewhere for $125, so that's not a bad in-house deal). Otherwise if you're looking for less expensive options, I don't see anything at MC that is priced well. Newegg has a PowerColor R7 250X for $80(shipped), which is substantially (like 3X) more powerful than the GT730 that the microcenter representative suggested to you. In fact, the R7 250X can play any game that has ever been made at 720P with smooth FPS.

Moving on to the PSU. Here again, MC is pretty non-competitive. They are offering the usual suspects, mediocre quality CXXXX and EVGA XXXB unit for ~$50-75. The same price range elsewhere buys fantastic quality and higher efficiency PSU's. The Rosewill Capstone 450W is pretty consistently $60 shipped from Newegg and Amazon, which is about what you'll pay for the much worse, and much less versatile CX430 with tax over at MC.

Finally, the FX-8320E ships with a pretty weak CPU cooler. You can use it, but my advise would be to replace it with a basic heatpipe cooler. However, there may or may not be room in the HP case for it, as *some* of these very compact mATX cases will have the optical drive hanging back over the motherboard far enough that the HSF won't fit. You might wait till after you have assembled this to measure around the socket. The HSF I recommend is the Rajintek Aidos for $23 from Amazon.

--------

In Summary:

CPU: FX-8320E from MC for $100+tax
HSF: (optional)... Rajintek Aidos from Amazon for $23
MOBO: GA-78LMT-USB3 from MC for $15+tax
RAM: Re-use 3X2GB
GPU: R7 250X from newegg for $80
Storage: Re-use? otherwise pick up an MX100 256GB from Amazon for $100
PSU: Rosewill Capstone 450W from Amazon/Newegg for $60
Case: Re-use for now.

That's $270 (or $370 if you add an SSD) + $23 for the optional HSF.

-----------

If you want to better prepare the stuff you are buying now for overclocking, switch the motherboard selection to the GA-970A-UD3P + FX-8320E. Price will be $160 with tax. (FYI, the same combo would cost ~$225 anywhere else).

The UD3P is a ATX board, you'll need a new case to fit that. On measure, the comparably priced UD3P is so much better than the 970 Extreme3 that it's a wonder they can sell those Extreme3's at all. (unfortunately, there are many junk motherboards in the industry, and they depend on ignorance to sell).

Cases are an area where MC is competitively priced. The $40-60 range is rich with options, mostly the same options you'll find elsewhere for about the same money. They have a Fractal Design Core 3500 there for $75, which, if you're willing to spend the extra would open up your options to all sorts of larger format CPU cooling, and offers the best cable management you'll find in any case in its class. It even has room behind the motherboard tray to hang a fan to cool the motherboard socket.

On the GA-78LMT-USB3 the capstone would be fine with anything but the most radical GPU's made (special non-reference models with more than 2x8 pin connections or dual-GPU units).

Logain is right though, for the UD3P alternate, I would advise going with a 550-650W size as well, sorry, forgot to mention that. That board can comfortably support overclocking to ~200W at the socket, so the system can wind up near 300W before the GPU is considered. A Rajintek Themis EVO would be a nice value HSF option there.