Which desktop is better value?

I would go for the new. You would need to replace PSU and SSD drives are flakey, mine Blue Screens almost every boot up. So by the time your done you've replaced most everything. Also the new one would last about 5-6 years working well where the used would be outdated again in 2-3 years. I build a lot of my own computers and it makes it easier for later upgrades if you build your own. So yearly costs would be the same about 100 pounds. It's called ROI in business, Return On Investment. So for the same 100 pounds a year you would have a much better computer with the new one. I hope this makes sense and helps.

Build your own, but unless you plan some serious multitasking with heavy duty apps like CAD design and professional HD video editing, there is no need for an i7-3770K.

For gaming and video editing and everything else, i5-3570K does the exact same great job for £70 less.

Also, you don't need a sound card, except if you do heavy professional sound recording and editing, all modern motherboards have excellent onboard HD Audio, 8 channel (7.1 surround)

i would always go for "own" build over a second hand one, you never know what the last owner did to the pc, overlcocking etc. what cpu does the first one come with. ?

the motherboard on the pc does handle above 1333mhz ram, infact it will handle

4 x DIMM, Max. 32GB, DDR3 2200(O.C.)/2133(O.C.)/1866(O.C.)/1600/1333/1066 MHz Non-ECC, Un-buffered Memory found here http://uk.asus.com/Motherboards/Intel_Socket_1155/...

Either way i would go for the own build, a 7770 will req a higher psu than a 460w power supply also it requires a min of 500w, along with the extra ram and high grade cpu i wouldnt trust it,

the 650w one you selected on the own build would be much better.

second by far but id swap the processor and buy a nvidia graphics card like the GTX 660ti.

Own build of course much better specs