I was incredibly paranoid about cooling my first build, so this is what I came up with:
Intel i5-2500K (i3's are the suck, i7's are mostly overkill for gaming)
Biostar TZ77B LGA1155 mobo
8GB G.skill Ripjaws X @ 2133MHz
OCZ Agility 3 120GB SSHD
PowerColor Radeon HD6850
Corsair H60 closed-loop water cooler
Apevia 680W PSU
NZXT Source 210 case, plus an extra fan
All for $762 on the nose. I've since added a WD Caviar Blue 1TB HDD since I like to download YouTube videos and watch them at my leisure without the annoyances, but if it wasn't for that I would have been fine with the SSHD. Unless you do video editing or something (or you're a rampant pirate, yarr), mega high capacity drives are /probably/ unnecessary. But again, you can always add more HDDs.
2133Mhz ram is so far overkill it's insane. 1600 is the 'standard' these days, but you'll hardly see any improvement over 1333 anyway. G.Skill is good though.
If this is his first computer being built on his own, I very much doubt he'll be overclocking. Z77 and K arent going to be helpful. Look at a H67
(77 is IvyBridge, not Sandybridge) and non-k. I do agree on the cooling though, and the H60 is a fine choice for a non-overclocked CPU.
I3's are most certainly not "the suck", Pentiums and Celerons are "the suck". You have about 8x the needed CPU power to keep up with the GPU you chose, considering an i3 isn't even held back by a 680 or 7970. This is a serious unbalance. Also, the 6850 get's it's ass kicked by the smaller and cheaper 7770 in price, preformance, and power consumption with the latest drivers.
OCZ has not been a trusted SSD brand in quite some time, especially the ones with SandForce controllers. The Samsung 830 for the same price
offers faster read/write, more IOPS, more storage, and better reliability.
Apevia is really truly not a good PSU brand, and that's an even worse PSU then the norm. Stick with SeaSonic, Corsair (rebranded SeaSonic), Rosewill, Antec, Thermaltake, or Silverstone PSUs for anything under $80 or so. At least they offer the wattage they write on the side.
It mostly comes down to knowing where to look for quality parts.
One thing to keep in mind if you build your own PC: airflow airflow airflow. Even pre-built PC manufacturers are terrible at this. Hurr durr let's make the side fan exhaust so there's no cool air blowing over the mobo and no cool air for the CPU cooler to draw over the heatsink! Great idea!
Don't overthink it but ideally you want to do a couple of things:
1) The motherboard needs cool air. There are a few hotspots (the northbridge and southbridge, for you savvy ones) that really should be cooled.
2) Your CPU cooler NEEDS an inflow of cool air to work properly. If there's nothing but hot air circulating in the case, it can't magically cool it down before it blows it through the heatsink.
3) Your graphics card? Same thing. Most of them suck in air through the fan and blow it out the back of the case. If they're sucking in warm air, they're not gonna work well, and modern GPUs get hot.
4) Don't fight convection, goddammit. Hot air rises. Cool air sinks. High school freshman science there. Exhaust out the top of the case, intake near the bottom. Make sure your fans aren't fighting nature. Nature always wins. Also make sure they aren't fighting each other.
5) DUST. If the place you live has lots of dust, or especially pets, you may want to consider air filters, or a positive-pressure cooling setup (basically means there's more intake than exhaust, which makes the inside of the case slightly pressurized - any little screw holes/gaps, instead of letting dust in, will constantly be venting air instead). It sounds complicated, but it's really not. More fans blowing in than fans blowing out, assuming they're the same size, of course. Also, forgot commercial air filters. They kill airflow. I've been using...wait for it...dryer sheets. Yes, those little guys you throw in the dryer to kill static.
If a first-timer like me can figure all this out, I'm sure OP can. This is probably the most intelligent and computer savvy community I've been a (small) part of. Good luck! If you decide to build, that is, OP.
When you have an H60 and a cagefan GPU, that all goes out the window. There is nothing inside the case to heat anything anymore. The GPU and CPU heat it up, sure, but all that heat goes straight out the back.
1: The motherboard is just fine. It does not need airflow like the CPU and GPU do. The standard case fans are enough. (Intel boards also do not have a NorthBridge, it's on the CPU now)
2: One fan in back and one in front usualy gets rid of that unless the case isnt made correctly.
3: Modern GPUs run cold as hell compared to, say, the 400 and 500 series.
4: Convection doesn't mean **** inside a computer case if you have the fans to push the air around. There are many people who mount a 240/360 rad on top, have the side, front, top and bottom as intake and let it shove all the hot air out the back.
5: Always go Positive air pressure. It'll just make life easier. Also, pantyhoes make good filters. Fan size has nothing to do with it, there are 120mm fans that push 30cfm, and there are 120mm fans that push 250cfm. Always try to know the CFM rating, because that is the only value (besides how much noise it makes) that matters.