Getting BEAST v8.5c eGPU + GeForce Cards To Work With Z61p ExpressCard Socket

[Shredder11]

I'm currently attempting some upgrades on a Z61p machine. I needed the ExpressCard socket for an eGPU purpose, which had a USB 3.0 + eSATA port adapter in it. I've also swapped the internal WiFi card for a USB 3.0 PCIe card, and then ran a short extension cable through the back with a socket on; this does not work/undetected by Windows XP. This was to free up my ExpressCard slot for my eGPU card and adapter.

I tried a few graphics cards plugged into a BEAST v8.5c eGPU host adapter, including an old desktop Geforce GTX550-Ti, to fully DSP power a convolution reverb plugin. https://gpuimpulsereverb.de/. This did not work no matter what BIOS display settings I used, or when I powered it up (pre / post Windows booted). I tried a GeForce GT610 again with no card detected by Windows XP Pro SP3 32-bit. I tried an ATi HD6570 card and that worked, but sadly it messed up the existing drivers used with the integrated FireGL v5200 GPU chip of the Thinkpad. I then decided to try my Thinkpad T43p and both the GeForce cards worked fine in the same BEAST eGPU adapter in the ExpressCard socket, Win XP etc. I did not bother trying the ATi card as the T43p also has an onboard ATi GPU chip.

So I am wondering what is causing the Z61p to not recognise the GeForce cards? I thought it might be that the T43p has 2GB RAM and the Z61p has 3GB RAM, but the ATi card worked with 3GB so not sure this is the issue.

Anyone any ideas as to why the same setup works with the older Thinkpad T43p and not the slightly newer Z61p? Can the discrete ATI Mobility FIREGL V5200 chip be disabled at hardware level?