ASIO Performance Spikes in Artist 8.5.20 - Help

The title says it all really.

Running a Dell Optiplex 780 (latest bios - A18), 4GB RAM, i7 (2600) 3.4GHz processor, Sapphire AMD Radeon HD 5450 1GB, Focusrite Saffire 2i4 2nd Gen.

I had 8.5.20 (32-Bit) working perfectly until recently. Now at some random time, typically 2-3 minutes the CPU average hits 100% and causes a dropout, even if it’s running at 20-30%. DPC Latency Mon and Latency Check shows no issues for processors but occasional page file faults but nothing to suggest any issues.

Having read many threads on this, I have:

  • Switched off power saving in BIOS.
  • Disabled c-states in BIOS
  • Changed power settings to highest performance (ie no hibernation / sleeping) but have not used Steinberg Power Scheme.
  • Changed the NVidia video card for the Radeon and installed latest driver - only driver was installed, no other software.
  • Changed an Alesis io|2 for the Focusrite with latest drivers (4.15) installed.
  • Ensured the USB mouse and Focusrite are on difference USB hubs.
  • Updated the NIC driver to latest from Intel site (cured the spike every 4s observed on DPC Monitor)
  • Updated the USB drivers to latest Intel drivers.
  • Tried Cubase with ASIO guard on and off.
  • Tried ASIO4ALL, Generic ASIO and Focusrite ASIO Drivers.

Nothing seems to make any difference and I can’t see a link between a particular activity or plugin(s) used and causing the spike - it happens regardless of the amount of tracks / plugins used.

The only things I can think of that are left to try are a complete reinstall (I’d rather not), install a USB 3.0 adaptor card for the Focusrite, roll back to Windows 7, buy a new PC or finish with Cubase.

Can anyone offer any advice now I feel like I’ve wasted the thick end of £300 on an installation of Cubase I can’t use?

Thanks in advance