I just swapped my HDSP 9632 PCI card into a new i7 machine and was surprised to see only a modest improvement in ASIO performance, compared to the ancient Q9300 Quad rig from which the card was just removed.

My DAW host is Cubase 6.5 and ASIO performance is relatively poor in both the 32-bit and 64-bit versions, with 32-bit and 64-bit versions of the same plug-ins.  The ASIO meter behaviour also seems a bit unusual.  Instead of gradually building toward maximum, it becomes jittery and starts spiking, sometimes with only a handful of resource-intensive plug instances, and a CPU load of only ~30%. 

The new i7 2600k machine is running Windows 7, with just a few basic tweaks.  The only other card is a UAD2.  I'm using the mobo's integrated graphics.  All drivers and bios are up to date and DPC Latency Checker shows average latency under 100 usecs. 

Everything seems to be in order, *except* of course that the motherboard (Asus P8Z68-V Pro GEN3) does not natively support PCI and instead uses a PCI-to-PCIe bridge chip.

Could the PCI-to-PCIe bridge be the cause of the modest ASIO gain between the Q9300 and i7 machines?

If I upgrade to a PCIe RME card, will I see a more impressive improvement?

Thanks for any help or suggestions!