64 bit: is it worth it?

[LeftyAce]

Hi all,
I'm researching to build a gaming rig for around $1000, and understand that AMD is probably the way to go. I also read that the X2 processor isn't going to help games (they're single threaded). MY question is, since I'll be using XP, (and I hear the 64 bit edition is pretty useless) is getting an athalon 64 worth it? Or should I stick with some kind of 32 bit processor? Do 64 bit patches for games work regardless of the os? and if everything on the comp is 32 bit, does the architecture of a 64 bit proc. help me out any way?

Thanks,

N3wo

[Force Flow]

You *can* get a 64-bit CPU and run it at 32-bit (and most of them will fly).

The AMD Athlon 64 3700+ San Diego core is quite popular for gaming builds these days, albeit a tad on the expensive side (pushing $210).

[doctorgonzo]

Getting Windows x64 may not be worth it (I use it, but there aren't great performance boosts or anything), but 64-bit processors work just fine even if you aren't using an 64-bit OS. You just won't get all of the benefits of the 64-bit platform. Speed increases from faster clock speeds and more powerful processors you will get, though.

You may not know this, but processors like the Athlon 64 can work just fine with 16-bit DOS! For reasons of compatibilty, all x86 processors start up in 16-bit mode, then switch to 32-bit mode if necessary (like for Windows, Linux, and all modern OSes), then switch to 64-bit mode if necessary again (like for Windows x64).

[LeftyAce]

Thanks for the info guys. I knew the 64 bit would work, but I was wondering if it was better even though it is running in 32 bit mode. Someone told me the memory bandwidth is twice as big? or the caches are bigger or something.
I didnt know that they were 16 bit capable! Thats interesting (although running one in 16 bit dos seems like a waste....and I heard DOS isn't the best os for modern FPSs :-)

So buy a 64 bit proc even with standard WinXP? (still gives a performance boost??)

[jimmyrules712]

ignoring the fact that the athlon64 is a 64 bit CPU and it's still an awesome CPU. The fact that it can run in 64 bit mode is not the only good thing about it, so you'll still be able to enjoy plenty of it's speed benefits running in regular windows XP.

I would buy an athlon64 if I were you. But to be fair, Intel probably offers a few CPUs that may be just as fast at a comparable price.

[blue60007]

If you had two identical CPUs with one having 64bit capabilities and the other not, the performance would be identical. If you are upgrading from something older it's going to be the higher clock speeds/more cache/etc that will give you the performance boost; not the 64bit capabilities. Even with a 64bit OS and 64 patches for the occasional game the performance gain just isn't there.

I think the difference is that 64 bit CPUs can handle 64bit wide chunks of data; something to that extent. Hopefully someone else can expand on that. It's kinda like multi-threading: unless a program is written very well to take advantage of 64 bit (or multi-threading) you won't see much performance boost.

One interesting note, a 64 bit CPU can theoretically support up to 17,179,869,184 GB of RAM (2^64 bytes). 32bit CPUs can only support up to 2^32 bytes, or 4 GB.

On the other end of the spectrum, Intel also offers CPUs with EMT64 capabilities. I don't think it's a true 64 bit architechture, but it's close. It's hard to tell if it's any slower as I don't think there's any programs that can truely take advantage of 64bit.