Some examples:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128403
That one is probably priced so high because (unlike some/most 1156 boards) it seems to be able to fully support running 2 graphics cards in crossfire or sli. Is this incorrect, or is there something else, too?
The UD6 is Gigabyte's top-of-the-line P55 motherboard, and comes with almost all the bells and whistles that an overclocker has come to expect: 20+ power phases, 10 internal SATA ports, SLI connectivity, dual gigabit LAN ports and so on. Most of this stuff is stuff that your typical DIY computer builder or light overclocker won't need (even if they've been conditioned to think they need this stuff).
If you ever feel you have need for such a motherboard, you might as well go for the
P55A-UD6 instead, which is only pricier by the cost of shipping, and comes with USB3 and SATA 6Gbps for futureproofing.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813121385
... Now this I'm completely kind of baffled by. Are a few extra ports worth twice the price, or is it just that there's something else that I'm not seeing here? <.<;
I'm just wondering if there's any real gain for me in purchasing a more expensive one. Otherwise, I think I'll stick with the ASUS board.. but I also want to make sure that I'm not missing out on something important.
It's an Intel board; for some reason, all of Intel's boards for the higher-end chipsets seem to be priced higher than the competition. The only advantage I see an Intel board having over the competition is the use of an Intel network chip, which are generally acknowledged to be better (by however small an amount) than the usual Marvell/Realtek network chips. And if you believe Intel's engineering department to be better than those of other motherboard manufacturing companies, that may play a part too.
In my opinion, Intel P55 boards above $150 are already in the overpriced range. Unlike P45 boards where you're actually paying for the northbridge (P45) + southbridge (ICH10) chip, when you buy a P55 board you are only buying the P55 chip (which is a southbridge, known in marketing terms as a Peripheral Controller Hub). The southbridge generally costs much less than the northbridge, since it does less work (I/O wise; the northbridge handles memory and PCIe graphics transactions while the southbridge handles networking, storage and PCI + some PCIe transactions, which is generally a smaller load).
Technicalities aside, you're paying the same price as a P45 board even though you're getting one less chip (and it's a pretty important chip too; if you're wondering why you don't need this chip on a P55 motherboard, it's because it's been integrated into the CPU). For that reason alone, even a $100 P55 motherboard is already overpriced.
Add to that an additional storage controller (which gives 4 SATA ports in addition to the 6 already on the P55), HD audio chip, MOSFET coolers (those showy heatsinks around the CPU area, which you generally do not need if you have decent cooling in your case or are an extreme overclocker) and SLI branding, and you have a "high-end" motherboard that is really just a southbridge with lots of third-party addons (and which isn't even capable of triple-SLI without a PCIe bridge chip).
While it is true that a good motherboard is essential to system stability, $200 is way too much to be paying for a motherboard that only has a southbridge. The Gigabyte P55M-UD2 is proof of this, and in fact, it can still afford to be cheaper; I suspect the main reason it isn't priced at $80 is to avoid cannibalising into sales of P45 motherboards. This isn't something that motherboard makers can't really do much about, since Intel sells them P55 chips for slightly less than the price of a P45+ICH10 (and the P55 is nothing more than a tweaked ICH10).
So anyway, no, you do not benefit from buying a pricier P55 motherboard, not when you've already picked a motherboard that fits your needs very well for ~$105 anyway. I base this conclusion on your declaration that you won't be using more than 1 graphics card, and you don't sound like the kind of person who would be trying to break 5GHz on an i5 (which is currently impossible, anyway).
Lastly, contrary to popular belief, you won't actually need a 500+W PSU; in fact, if you can accept the idea, a good 450W PSU is already sufficient for your needs.
Anandtech.comYou can easily see that any of the single-GPU cards gives a system power draw under 400W, even when under load. You will probably want to add another 100W for dual-GPU cards (e.g. GTX295, and ATi X2 cards), but otherwise these numbers are generally valid (you might want to include your own safety margins).
I can't remember if Anandtech's power consumption numbers are consumption-at-wall or DC consumption only, but even if we assume a minimum PSU efficiency of 80% (which is valid if you're using an 80plus-certified PSU; the Corsair PSUs certainly are), system power consumption of 320W means you're just clear at 400W. A 450W PSU will give you 50W of "breathing space" at load; you can go for 500W if you like a bit more "breathing space", but do note that most of the well-built power supplies let you draw more power than they are rated for, for short periods of time, so you're already covered for transient power spikes.
Why should/shouldn't you use a higher-rated PSU then? This isn't necessary reading (even if I like to think it is), so I'll put it in spoiler tags.
Here, I should first say that buying a PSU based on its max allowable load is usually not advisable; good PSUs generally will let you draw at least 50W or even 100W higher than their ratings suggest, without blowing up. Bad PSUs, on the other hand, may exhibit problems before you even reach their rated allowable capacity. Remember that the power rating is set by the manufacturer, nd not determined by some standardised process. Good PSUs may be rated lower than they can actually output (as in the case of Corsair) so that they can be 80plus-certified (>80% efficient at 20%, 50% and 100% power draw relative to their rated power), and bad PSUs may be rated higher (don't ask me why).
PSUs typically are most efficient around 40% to 60% load. You can look up PSU reviews, or some PSUs will have a label that shows the efficiency curve of the PSU. You generally want to be operating near or at the peak part of the efficiency curve (i.e. 250W for a 500W PSU, 400W for an 800W PSU, etc). It won't kill you if you don't, but at max PSU efficiency you draw less power (not too important for most people), and your PSU does not produce as much unnecessary heat (which could be a big win for you if case heating is an issue).
The typical desktop idles at ~100W - 140W or so, but you can't possibly run your build with just a 300W PSU, so if you only expect to be at full load for a short time, picking a 500W-rated PSU is a good choice. But if you're a 24/7 gamer/encoder and your desktop is pulling 350W all the time, than a 700W PSU makes sense. If you're somewhere in-between, it makes sense for you to get something between the two.
At other times, you may have to use a higher-rated PSU than you intend to; for instance, some people like having dual-rail PSUs (this basically just describes how the current is distributed by the PSU: over 1 'rail', or 2 'rails', or more). Most cheaper 500W PSUs are single-rail, and you will only see dual-rail designs on higher-rated PSUs. generally you buy a higher-rated PSU for the feature set, or if you intend to upgrade or add to your build without upgrading the PSU.
In short, don't buy a PSU just for the rated wattage; there're other factors that come into play as well but I'll leave those for another time.
