Are they available to a JTAG probe? I've not looked at a modern motherboard in ages, but I wouldn't be too surprised to find unpopulated JTAG pads near the CPU.
Why not? Even if it doesn't use JTAG for debug, it almost certainly would need it for boundary scan. I just checked volume 1 of the Intel i7 processor family datasheet, and it does show a JTAG port.
