On Mon, 21 Mar 2005 13:41:41 -0500, Ivica Ico Bukvic <ico@xxxxxxxx> wrote: > > I have an amd64 running in 64 bit mode. There honestly isn't much > > reason to get a 64 if you are going to run in 32 bit mode...They are > > way more expensive than the 32 bit counterparts and don't offer enough > > extra in 32 bit mode. > > FWIW, I strongly disagree. You get much better performance per clock on a > 64-bit machine even when running in 32-bit simply due to chip architecture > improvements including SSE2 among other things, and the price should not be > that different when compared with the 32-bit offering (as long as you don't > go for the FX stuff). Also, heat dissipation as well as battery life (if > considering laptop) is definitely a plus when compared with Pentium4 > offering. Pentium-M processors are also nice but also generally more > expensive. I am of course not talking about Intel processors, which are always way overpriced, when I compare price between 64bit and 32bit. Maybe the prices of 64 AMDs has gone down considerably but when I bought mine the price was at least 5x greater than a 32 bit at the same speed. BTW, I am pretty sure the SSE2 registers are only available in 64bit mode. I used the amd64 as my target platform in my os "design" for college. If I recall correctly the SSE2 registers are one of many things that become unavailable in 32bit legacy mode (the mode used when you run a 32 bit OS), and this includes the expanded memory addressing. In compatability mode, where the os is 64bit but the app is 32, they might be available. I could have my mode names reversed... In short, when you run the 64bit processor as a 32bit processor you loose almost all of the enhancements made in the new design. You probably actually have better features with an actual 32 bit processor than you do with a 64 in 32 mode.
