Man-wai Chang to The Door (33600bps) wrote:

The circuitry is all there, but they disable it? I know that some
circuit boards have uninstalled component locations, but all of
the stuff is there and disabled?

AMD must have a good reason to not sell them as 4-core CPUs. Any one
knew why? Is it a secret?


It allows them to get some value from defective quad core chips.

The quad core chip would be a relatively large silicon die.
If one or two of the cores had some small problem, the wafer
sort process could identify them as candidates for packaging
as dual core processors.

The AMD test will test all sorts of stuff that never
arises in normal usage. Compilers don't use or emit code
for all possible instructions on the processor. Only a
small subset of all possible instructions is generated
by the average compiler. (An evil person writing assembler
code can do that, if they want.)

The thing that is defective, might be something not normally
used. In other words, it is highly unlikely that the end user
will be able to figure out what is broken in the unlocked cores.
My suggestion to use Prime95 is only a bit of a test - by
no stretch of the imagination is it a complete test.

Or, the thing that is defective, might only be defective at
elevated clock rate. If you're making processors, you likely
test them at a few hundred MHz above the stated operating
frequency. That takes some aging and parameter shifting into
account over time.

Paul