Apparently the SSD in HP laptops uses wireless to communicate rather than a wired circuit as with regular hard drives. So even when you disable all wireless antennas and drivers, the computer continues to emit radiation and the levels are not insignificant. We measured about 0.5 Milliwatt/m2.
How did we discover it? A friend bought a new laptop and although I disabled all relevant drivers, it continued to emit RF. I identify the area from which the transmission was coming - it was on the right side, near the edge in the middle.
I contacted HP tech department and after an hour on the phone they confirmed that the reason for the RF is that while the SATA drive connects internally with a wired circuit, the SSD connects wirelessly.