how often is the website cache in google reindexed

my cache is showing white line in page rank

[mr wonderful]

How often is the cache in google spidered. Is it every website every month or can it take alot longer?
Thank in advance you for you help.

[Dolemite]

Cached versions never have a PR and are never spidered.

The cache is updated after either deepbot or freshbot visits a page, so the update frequency depends on when the bots visit.