In case anyone is interested in building a new PC for their aging PCI PTHD system, to squeeze another few years out of it, I can announce that my new build has been successful.
I wanted to do an Intel Sandybridge build to get the most out of the system, but as many of you may know, most of the chipsets available (P67, H67, Z68, etc.) do NOT have native PCI. Instead they use 3rd party PCI-PCIe bridges, which the PTHD cards do NOT like at all.
So, I did my homework and discovered that the Intel C202, C204 and C206 chipsets for the Xeon range of Sandybridge CPUs do in fact have a native PCI implementation, and as such should play nice with the PCI PTHD cards, in theory.
My system includes PT HD2 and three PCIe UAD-1e cards, so my needs in terms of the PCI/PCIe slot configuration of the motherboard are quite specific. I finally found a mobo with exactly the configuration I need, based on the C202 chipset. So, I bought the parts and rolled the dice.
Some of you may have seen my other thread about my TDM Core Card frying in the new system a couple of weeks ago. I am delighted to report that this was not caused by a faulty motherboard. I can't say for certain what caused it, but I have rebuilt the new system with a new high-spec PSU and a replacement PCI Core Card and she is running very well indeed with the very same motherboard, even with the burnt plastic on the PCI slot.
To play it safe, I cut off the superfluous PCI-X pins from my two TDM cards with an electric dremel, in case their contacting something on the motherboard had caused the first Core Card to fry.
The difference in power compared to my old system is HUGE. My previous system was about 4 years old, based on a Core2Quad Q9450 CPU with 4GB of RAM. The new CPU is a Xeon E3-1270, which is basically the same as an i7-2600, but without the GPU of the i7 and with the extra server-related Xeon features, which I won't use, besides for ECC RAM support, which I am using.
Playing back a big mix that I had done recently, which was completely maxing out the old system to the point of instability and related headaches, on the new system the CPU meter in PT is hovering around 20-25% with very occassional spikes up to 40-50%. This is with 4 out of 8 CPUs (threads) allocated to PT in the Playback Engine settings. I think that the three UAD-1e cards are largely responsible for the CPU spikes and hope that this would be reduced or entirely eliminated by either replacing them with a UAD-2 or simply removing them and kicking the UAD habit altogether.
So, the moral of the story is that YES! You can build a current generation Intel Sandybridge computer for your PCI PTHD system! Go with a Xeon CPU and you will have a FAR greater choice of motherboards because the native PCI implementation of the C202, C204 and C206 chipsets works just fine with PTHD systems.
The parts in my system are:
CPU - Xeon E3-1270
Motherboard - ASUS P8B-X
RAM - 4 x Kingston 4GB KVR1333D3E9S/4G
(16GB in total)
PSU - Seasonic Platinum 1000
I hope that this post will be of some use to someone.