Hi POSTMAN477 and
The main difference is that the Newcastle core was the same type as in the 32 bit cpus and uses the same 130nm process as the 32 bit did.
The later Winchecter and Venice ones use a 90nm process.
They also run at a slightly lower voltage so they run cooler and should run quieter than the Newcastle ones.
They all have 512KB of L2 cache.
It appears that they all have Hyper Transport Technology.
I am not sure what the difference is between the Winchester and the Venice is, but it seems that the Venice overlaps with the Winchester and goes to a higher speed.
The San Diego core has 1MB of L2 cache but is over your limit unfortunately
This looks like it should do what you want :
http://www.ebuyer.com/customer/products/index.html?action=c2hvd19wcm9kdWN0X292ZXJ2aWV3&product_uid=88107I hope this is helpful to you and not too confusing