Motherboard blowing up?

In that situation, it's usually the PSU that "blows up" and kills everything, not the motherboard. Usually when a motherboard dies, it goes quietly and by itself, but if a PSU dies, it can take everything connected to it with it, especially if it's a low quality unit.

So no, a motherboard doesn't usually "blow up" on its own and take anything else with it. It just dies.

Its very rare for a newer motherboard to do this, there was a rash of this many years ago when a very large amount of bad capacitors shipped to manufactures but that was resolved long ago and most modern high end board now use solid state caps. However I have seen cheap and/or overloaded power supplies take out multiple components many times.

I'll be getting this motherboard
http://www.amazon.com/gp/product/B005KSBDDK/ref=oh_deta...

And this power supply
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Are these good parts that won't explode?

They're good for what they are, yes. Just don't plan on running a high end GPU with that PSU or anything. I'm guessing that since you're getting that board, that you're NOT planning on that though, and that you're planning on using just the integrated GPU of the APU, so it'll be fine, in that case.

I'm gonna use A8-3870k with the integrated gpu also gonna crossfire 6670 with it.

That should be ok then.

I would get a different PSU for that config while in theory it should work, 400w is the minimum recommended for the card and I never suggested running the minimum, you always want to leave a bit of breathing room. Also in the last couple years I have seen a lot of issues with the smaller Antec power supplies(anything below 600w seems to die quickly). For power supplies I stick with PC Power and Cooling, Corsair and Seasonic.

I already bought the power supply  
For 50 dollars, shouldn't it be good quality? I got it on sale for 30 bucks.

Dust is a big problem and can be a major cause to things "blowing up" in a PC. If an accummulation of dust builds up on a circuit that is likely to get hot then it could cause the dust to smoulder and cause a "fire". Vacuum around the PC often to avoid dust accummulation.

Avoid putting the PC where there is likely to be dampness or high humidity.

Asus is a good brand and I doubt that you will have problems apart form user irresponsibility.

The Psu is good enough for onboard GPu or a low to mid ranged video card but I'd suggest 700 watts or more if you intend on using Crossfire, or a 2gb video card.

700 watts?! That's a LOT, I used the power supply calculator and it was only like 250-350watts required. I might get the 2gb 6670 card and crossfire, will my psu be able to use it?

I think he's thinking REAL Crossfire, not Hybrid, like you'll be doing. Hybrid only requires enough power for ONE GPU not two.

400W is on the low end of what I would like, but it should still work for you.

"For 50 dollars, shouldn't it be good quality?" Maybe, maybe not, there's alot more to a quality PSU than price, but the nice ones are usually not the cheap ones. Quality or not it only meets the minimum requirements which means it will be running at or close to all out when under a load this will drastically shorten the PSU's life and when a PSU dies it often doesn't go alone. As mentioned it should work. However for how long. 700w is kinda much Id suggest atleast a 500W. Here's a Seasonic 520w PSU for $70 - 15%(Sale)=$61.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I already bought the 400w psu  
When I posted a thread for help I forgot to mention that I was going to crossfire with 6670 so everyone said the 400w psu would be fine.

As I said in the post you just quoted. The 400w psu will work but its going to be running at or very close to its max with a 6670, running a PSu at max will shorten its life expectancy and when a PSU fails many times it takes other hardware with it. A system that belonged to a freind that had a 500w PC power and Cooling psu(high quality psu) originally had a single 8800gt and later added a 2nd in SLI without upgrading as 500w was the min recommended. The system ran just fine for several months then the psu popped. When it died it took 1 video card, the motherboard, ram, and a HDD with it. Only the backup hdd, cpu, optical drive and 1 video card survived. Since then I have seen and heard of many similar incidences, and I personally choose the safer route. It may not guarantee no problems but it certainly lowers the chances of a failure. Have you already bought the video card?

Haven't bought the video card yet but I bought everything else, so I need a new psu now,   will newegg take a return and give me a full refund?

I used this psu calculator(http://extreme.outervision.com/PSUEngine) and put in my info and the recommended psu is like 305w. I really don't want to buy a new psu because the 400w one I bought just came today but I also really don't want to have my pc blown up in a few months.

Here's the info I put in the psu calculator

http://i.imgur.com/Sw5vb.jpg

I put 6450 and 6670 because 6450 is almost equal to 6550d and they didn't have a 6550d option. On the dvd drives part, I only have 1 dvd drive right? And I didn't know what PCI I had so I just put the soundblaster one because it says all models. The outcome was only 316 watts. I have 400 watts. Are these calculators reliable?

Asus's calculator says 400w is the minimum(had to use a 5670 as 6670 wasn't available the difference is the 6670 uses 2w more than the 5670).
http://support.asus.com/powersupply.aspx
NewEggs shows 331 but it only uses the basics.
http://images10.newegg.com/BizIntell/tool/psucalc/index...
Newegg does have a 30 day return policy so since you just received it, if you contact their cust support and explain you need to return it to buy a bigger one they may not charge a restocking fee.