  Depending on various assumptions on the energy scale of inflation and
assuming a primordial power spectrum of a Broken Scale Invariance (BSI) type,
we explore the possibility for Primordial Black Holes (PBH) and Planck relics
to contribute substantially to cold dark matter in the Universe. A recently
proposed possibility to produce planck relics in 4-dimensional string gravity
is considered. Possible experimental detection through gravitational waves is
further explored. We stress that inflation with a low energy scale, and also
possibly when Planck relics are produced, leads unavoidably to relics
originating from PBHs that are not effectively classical during their
formation, rendering the usual formalism inadequate for them.
