So this is what I get up to on my weekends...
Yesterday I took the two Asus P6T's with i7-920 CPU's off to the computer shop. I came back with two Asus P8Z77-V LE Plus's with i7-3770 CPU's. You can see one of them below.
Unfortunately they couldn't get a kit for the old Thermaltake 120mm heatsink so it got replaced by a Noctua NH9 (92mm) with 2 fans in a push-pull arrangement. I also replaced the memory as the old motherboard uses triple channel memory and the new one is dual channel.
Out of this I have gained a faster CPU that uses less watts, more memory and the newer graphics cards now have a PCIe 3 slot giving faster transfers.
On the down side I had to reinstall Windows due to the chipset drivers being totally different and the hard disk in one of them failed (its still under warranty). I also have a problem with the KVM cabling as the P8Z77 has only a single PS/2 port (it can be keyboard or mouse) but the KVM expects both. I will need to buy some USB KVM cables.
As the new motherboard has a couple of SATA III ports I have ordered two new hard disks, same size as before but SATA III and with a bigger cache.