Athlon iix4 vs Phenom iix4

The 945 is the better one because of the L3 Cache but it is not a big upgrade. Overclocking the 910 could give you the same results.

Switching from your PII X4 910 to an Athlon anything is not really an upgrade. It's actually stepping down into a lesser CPU model line. If you're looking to "upgrade" you should really only consider the PII X4 945 or 955. Both are great CPUs for gaming purposes. However as mentioned by rolli59, you could also simply consider installing a good quality CPU cooler and overclocking your existing CPU.

Odds are you'll barely notice the difference in 400mhz, the Phenom 945 is stronger than an Athlon II, but this upgrade just isn't worth the money unless your able to sell your current processor to cover most of the cost.

why not overclock your present processor?Spend your money for an aftermarket cpu cooler and they can benefit to produce the silmilar results
you can get from your present upgrade which is totally insignificant.Even though if you want a cpu upgrade why don't you try a black edition cpu
with a good cpu cooler or you can get a six core from the amd if your mobo can support that by any bios updates.if i were you i would not think of
upgrading from a phenom II to an athlon because the athlon lacks L3 cache which can a benefit for many applications.

L3 cache is considered the slowest of all cache levels and also the furthest..Even if you dont have it you really wouldnt recognize it..

Then why should the chip manufacturers like intel or amd include 6 mb or 8mb cache memory?
You know that the most part of the die in most of the performance chips is this cache and not the cores.
Even though the L3 cache is the slowest among all caches it is much much faster than the fastest ram available today.

Most applications can benefit from this large cache as you know the delay for reading data from memory is very large compared to delay
to read from any of the cpu caches.The design and introduction of Level 3 cache in addition to the L1 an L2 reduces the
number of memory read operations which affect the overall execution times.
So more the amount of cache greater the performance unless the program or software cannot use it efficiently.

So it is a great advantage to have large amount of cache and that is the main difference of a phenom from an athlon processor.