The problem is not noise, and the problem is not caused by protons. Energetic cosmic rays don't reach the Earth (usually). Instead they collide with molecules in the atmosphere, and the resultant particles from those collisions collide again. What reaches the Earth is a rain of neutrons. Those neutrons can be absorbed by the chip or by its surrounds. The neutron itself doesn't do damage. The damage results from the absorbed neutron making the atom into an unstable isotope. The alpha particles from the decay of that unstable isotope can do damage to the chip. It might flip a bit in memory (single event upset, aka soft error), it might cause a short circuit (single event latchup), or it might do something more serious (single event burnout).
People in the avionics industry have worried about single event effects for quite some time. Radiation is a big part of the reason that computers for aircraft and space vehicles are a decade or two behind the state of art -- and the gap is growing. State of the art in rad hardened processors are equivalents of the MIPS R3000 and the SPARC V8 (introduced for terrestrial use in 1988 and 1990).
Intel thinks the problem is serious right here, not just up in space. US patent 7,309,866, assigned to Intel, is for "Cosmic ray detectors for integrated circuit chips". From the background art description of the patent,
The normal background radiation environment on the surface of the Earth has ionizing components that sometimes affects the reliability of semiconductor integrated circuit chips, such as memory chips used in computers. If an intruding particle is near a p-n junction in the chip, it may induce a soft error, or single-event upset which can cause signals to change voltage and, accordingly, bits of data to change voltage value. Excess electron-hole pairs may be generated in the wake of the penetrating particle. The field in the neighborhood of the p-n junction, if sufficiently strong, separates these electrons and holes before they recombine, and sweeps the excess carriers of the appropriate sign to a nearby device contact. A random signal may be registered if this collected charge exceeds a critical threshold value.
Cosmic particles in the form of neutrons or protons can collide randomly with silicon nuclei in the chip and fragment some of them, producing alpha-particles and other secondary particles, including the recoiling nucleus. These can travel in all directions with energies which can be quite high (though of course less than the incoming nucleon energy). Alpha-particle tracks so produced can sometimes extend a hundred microns through the silicon. The track of an ionizing particle may extend a fraction of a micron to many microns through the chip volume of interest, generating in its wake electron-hole pairs at a rate of one pair per 3.6-eV (electronvolts) loss of energy. A typical track might represent a million pairs of holes and electron.
Cosmic ray induced computer crashes have occurred and are expected to increase with frequency as devices (for example, transistors) decrease in size in chips. This problem is projected to become a major limiter of computer reliability in the next decade.
Source:
http://patft.uspto.gov/netacgi/nph-...7,309,866.PN.&OS=PN/7,309,866&RS=PN/7,309,866