Review The arrival of AMD's Sempron 3400+ will come as no great surprise to anyone who has heard the rumours about its imminent launch. When it comes to budget processors AMD doesn't normally make big announcements, so those who've not kept up to date with the latest processor developments might wonder what the all the fuss is about, writes Lars-Goran Nilsson.

This time, there's a bit more to the chip than just a clock speed or cache increase - the Sempron 3400+ has been spruced up with some extra functionality. The 3400+ has a 2GHz core and 256KB of L2 cache, half that of an Athlon 64. The core has been shrunk and it's now built using 90nm technology. But what really matters is that the new Sempron core now supports 64-bit addressing and Intel's SSE 3 instruction set. The on-board memory controller has been tweaked, too, though in fact this was first done on the 3300+. According to AMD, the memory controller is more efficient, can handle memory modules of different sizes and if you populate all the memory slots with double-sided modules, the PC2700 speed limitation has been removed.

Up to now, AMD had reserved 64-bit support for the Athlon 64, but with Intel introducing 64-bit support to its Celeron range, AMD had little choice but to follow suit. SSE 3 has been inherited from the latest generation of Athlon 64s making the latest generation of Semprons more like the Athlon 64s than ever before.

The downside is that AMD has not moved the Sempron to Socket 939, so if you're interested in getting the new 3400+ you'll have to stick with a Socket 754 board and a pretty dead-end upgrade path. All the features of the 3400+ will eventually filter down through the various speed grades, although I would imagine that you'll have to wait for old stock to be sold out before they become available. In the meantime, all retail 64-bit Semprons will have clearly labelled boxes, but if you're looking at getting an OEM chip you have to keep an eye of for the product number; it should end with BO or BX for it to be a 64-bit CPU.

According to AMD, the Sempron processor speed ratings are not equivalent to that of Athlon 64 although it hasn't been specific as to exactly how they differ. Rather confusingly, a 3400+ Sempron is not comparable to a 3400+ Athlon 64; it is more like a 3000+, which is also clocked at 2GHz but with a larger 512KB cache. I'm not certain that 256KB of cache will make that much of a difference and, as you will see from the test results, the Sempron 3400+ put in some quite impressive numbers.