You misunderstand the attack. You don't need to sample at 1GHz. Each 0 and each 1 in private key material leads to calculations taking thousands of tens of thou

You misunderstand the attack. You don't need to sample at 1GHz. Each 0 and each 1 in private key material leads to calculations taking thousands of tens of thousands of clock cycles. So you only need to sample EM radiations at around 100 kHz or 1 MHz.