Advice about computer parts/PC building.

How much money are you able to spend on this build?
Also, are you able to order from newegg?

One small thing I spotted, the ram is SODIMM but you need DDR3 ram for the mobo/cpu. I would reccomend a 2x4gb set like you have though.

All other advice depends on the budget, but pcpartpicker is a really useful website for planning builds. There's different pcpartpicker subdomains for different countries.

Disclaimer: I don't compose music, but a friend of mine does, and there are some things that made a big differece to their performance.

At this point, I would advise against going with an AMD CPU. DAWs can be rather CPU intensive, so I'd rather wait and see if AMD's Zen core will be any good, and if not, go with an i5/i7.
I would also recommend 16GB of RAM for your workload - DDR3, not SODIMM.
That GPU won't really be suitable for any sort of more modern gaming, though it would probably be ok for 2D and less graphically intensive 3D games (think CounterStrike: Source, maybe GO). If you're not gaming, it will be fine.
I also can't stress enough the benefit of an SSD - makes things soooo much faster.
Pretty much all computer monitors worth talking about have a good response time, so I'm not too sure what you're looking for there.

Of course, this is all dependant on your budget, which you're yet to disclose!

Akatsuki wrote

My budget is about US$1200 (althought it was much less when i asked), i already have an SSD tho, i need the 1TB for samples and stems. I'll use my old case too because it's almost new. Should i get an i7?

Depending on the speed of a processor, you may as well go with a good i5 over an i7.  Your video card choice is very under powered, so it would be kind of overkill to use an i7 with that card.  Since you want the computer to compose music,  I can't imagine the video card is a big deal; however, for gaming, you will run into bottleneck issues with that video card long before an i5 processor.

I'm not really sure how much the processor becomes a factor with music software, but from what I understand, RAM plays a bigger role in performance in this area.  Also, for $1200, you can make a beastly machine! You might wanna reconsider your original build for future proofing.

36112
What specifically about it is underpowered? 4GB memory seems pretty solid to me

In terms of gaming performance, I would honestly expect it to be nothing short of pure garbage. 4GB of VRAM isn't going to help much if the GPU itself is really slow.
In terms of non-gaming performance, you'd probably be fine just sticking with the iGPU on the i5/i7. If that turns out to not be the case, you can always just add a GPU later.

36112
What specifically about it is underpowered? 4GB memory seems pretty solid to me

Memory is definitely not the most representative statistic on a graphics card. Low-end cards with low prices always have loads of vram, sometimes even more than high-end ones to trick the consumer into thinking they are better. The rule of thumb is that any card uner $100 is pretty trash.

If you already have a case I will omit it.

CPU:    i5-6600K
MoBo:  Z170X-UD3
GPU:    Gigabyte GTX 970
RAM:    G.Skill TridentZ 3200MHz 16GB (8GB x 2)
HDD:    WD black 1TB
PSU:     That sweet sweet 860XP2 (50% off at the time of this writing)
Total: $1,065.95

Red wrote

If you already have a case I will omit it.

CPU:    i5-6600K
MoBo:  Z170X-UD3
GPU:    Gigabyte GTX 970
RAM:    G.Skill TridentZ 3200MHz 16GB (8GB x 2)
HDD:    WD black 1TB
PSU:     That sweet sweet 860XP2 (50% off at the time of this writing)
Total:   $1,065.95

This is definitely a much better rig than the one in the OP.

You're definitely going to get a lot more out of this rig. If you're going to spend $1200, this is probably the most effective way of spending it.

If you don't want to get the 970 and aren't -much- of a gamer, and REALLY need more CPU power for something, I'd say drop down to a 780 Ti and grab an Intel 4-Core i7-4790K CPU for that 4.00 GHz

36217
 If you don't want to get the 970 and aren't -much- of a gamer, and REALLY need more
 CPU power for something, I'd say drop down to a 780 Ti and grab an Intel 4-Core
 i7-4790K CPU for that 4.00 GHz

Don't think the 4790k supports DDR4. Perhaps you meant the 6700k?

Red's build is a good one! Should work very well.