Athlon 64, 512Kb & 1Mb L2 cache, 32bit V 64bit question

[jayoinoz]

First post, so don't kill me if I leave something out!

Currently building my first rig and gonna stick an Athlon 64 3200+ in it. Now, this is sort of a Newcastle V Clawhammer question but not quite. There's loads of info about performance and OC'ing, etc out there. I've even read a post somewhere asking how to go about "enabling" the other 512Kb cache on a Newcastle! That's not what I'm asking.

Currently there's not much between these two CPUs - but what about in the near future? Seems 512Kb L2 cache is all you need in a 32bit environment. But what about a 64bit OS? If/when WinXP 64 comes out and I stick it onto my box, is 512Kb (if I get a Newcastle) going to be enough?

See, I'm not sure I have this right about 64bit at all. 64 bit instructions are longer, right? Like, twice as long as 32 bit? So will 1Mb cache running full 64 bit be similar to 512Kb running 32 bit OS? So how would a Newcastle fare?

Er, does anyone know what the h.e. double hockey sticks I'm talking about?

Thanks in advance.

 

[Mik3y]

yes it'll work fine. extra L2 cache has absolutely no effect on 64 bit. the reason why the newcastle exists is for cheaper production of cpu's. cache costs a lot of money to make, and for amd64 right now, 512k = 200mhz. which basically means that by giving the cpu only 512k cache, they can add 200mhz to it and it will basically break even. cache is an expensive way to increase performance, and because of the athlon 64's short pipelines, cache doesnt benefit amd as well as the P4.

 

[jayoinoz]

Thanks Mick3y! Looks like I'll go with the Newcastle core and put the savings into graphics. Seems that the s754 mobo arena has it's kinks worked out now too.

I'd figured (wrongly) that 64 bit would eat up the cache twice as quick.