From all I have read over the last 12 years I have been dabbling with 'computer music' I can confidently say, "It depends"!!
See, twelve tracks (at 24 bits, 44.1kHz) is WELL within the capabilities of this 6yr old, g6, i3 HP laptop upon which I type. It has 8G of ram but would not need more than 4G for 12 tracks..But! Start lobbing in plug ins, especially reverb and the CPU hit goes skyward.
I would suggest NOT an i7? The i5 is likely all the processor you will need (tho' I understand that there is no such thing as just "An i5" ? I am not THAT PC cute!) . Desktop for sure unless it HAS to be portable? (even then I would just bolt a handle on a tower!)
SSD (s) for sure. You want solid state for the OS and the DAW* but you could use a 1-2Tbyte spinner for samples and storage but also budget for a USB 3.0 external drive for 2nd back up (and arrange for it to be secured in a cupboard or something? I have had two fail, I know one at least was dropped. My 3.0 drive is on the floor!) .
Might be hard to find yet and pricey if you do but, try to get a MOBO that will support a PCIe Thunderbolt card. TB3 is the way ultra low latency AIs are going (there is also AVB and Dante but who knows which way to jump?) In any case PCIe can get you 4 more3.0 ports very cheaply.
*Some DAWs are grabbier than others. Cubase is V good but seems to want a lot of PC grunt? Reaper is very slim and efficient. My poison is Samplitude and that seems fairly low rent, does not seem to stress even lower spec PCS than this HP.
Dave (as ever, look to Sound on Sound forum as well)
