Build Upgrade Advise

[brightemo]

Planned Purchase Date: 6th September 2012
Budget: ~£400 GBP
System Usage: Gaming, Transcoding Video while streaming, 1080p playback, Internet
Location: United Kingdom
Parts Websites: ebuyer.co.uk scan.co.uk amazon.co.uk

What I currently have:

CPU: Intel Q6600 (4 cores at 2.4Ghz)
CPU-Cooler: Zalman CNPS 9700
MOBO: ASUS P5K-E/WIFI-AP (P35)
GPU: XFX HD 6950 2GB
RAM: 4GB (4 x 1GB) (Corsair DDR2 800MHz/PC2-6400 XMS2)
HDD: OCZ 120GB Vertex 2 (plus 2 Samsung HD103SJ Spinpoint F3 (1TB) for storage)
PSU: CoolerMaster 600W Silent Pro
Case: Coolermaster CM 690 II Advanced
Monitor: Philips 220WS8FS 22" TFT - 1680 x 1050
OS: Windows 7 x64

What I am thinking of upgrading to:

CPU: Intel Core i5-3570K 3.4GHz
CPU-Cooler: Noctua NH-D14
MOBO: ASRock Z77 Extreme4
RAM: 16GB (2 x 8GB) (Corsair Vengeance LP DDR3-1600)

Overclocking: Yes, CPU to about 4Ghz maybe? Something safe.

Why am I upgrading?: It has been a while. Also I seem to struggle with only 4GB RAM at the moment. And, of course, who doesn't like to get things done quicker?

So I guess my big question is what do you think about my choices? Will there be enough room for the Noctua NH-D14? I am a bit confused over all the advise to choosing between the 2500k (Sandy) vs the 3570k (Ivy). If I am not doing extreme (no idea what "extreme" would be) over-clocking is the 3750k better?

[GhOsT1321]

Clock for clock, ivy bridge is better that it's sandy bridge equivalent.
Ivy Produces less heat, but the smaller core tends to be hotter than sandy bridge. I say go with Ivy Bridge

[PP Mguire]

IB can still reach around 4.6 on that mammoth of a heatsink you have. As long as the Vengeance RAM you chose don't have the high heatsinks (the stupid little spikes on top) then clearance wont be an issue.

I don't really see the point in 16GB of RAM, but since you already have a decent GPU, an SSD, a storage drive, and an "ok" PSU I don't see a reason to try and cut costs. I say go for it.

[brightemo]

Thanks for the advice guys

[mocean]

Keep the CPU over clock by 2GHz and graphic card if external better to be overclock but not less then compare to CPU