New Phenom II X4 Innovations
On paper there are few real differences between the original Phenom and these new Phenom II processors. Now because they are pin compatible little has changed there, with the Phenom II processors actually dropping two pins rather than gaining any.
What has changed most notably is the operating frequency and the L3 cache capacity. The Phenom II X4 940 runs at 3.0GHz and the 920 gets along at 2.80GHz, which is still faster than any previous Phenom X4 processor. The Phenom X4 9950 for example was limited to a 2.60GHz clock frequency.
The original Phenom X4 featured a 2MB L3 cache, which has now been increased to 6MB on the Phenom II X4. They also feature what AMD calls "Enhanced Total Cache" which is a combination of dedicated L1 and L2 caches with a larger L3 cache that allows the cores to rapidly share information. Enhanced Total Cache manages caches diminishing latency on L2 cache accesses, while still enabling fast access to shared L3 cache data.
The L2 cache size and design has remained the same, with each core receiving its own dedicated 512KB. Combined, all four cores make for a total L2 cache capacity of 2MBs. Intel has adopted a similar caching structure on their Core i7 processors, giving them a smaller dedicated L2 cache with a much larger shared L3 cache, so clearly AMD is on to something here.