cache mem on newer cpu's

[jeepdinger]

what is the difference between the "newer" cpu's with the 256kb onboard cache and the older PIII and PII with the 512kb onboard cache? is one faster than the other? is the 256 equivalent to the 512 in speed and capacitity due to some new integration with the system? is anyone can fill me in on the change i'd appreciate it.

[Red Rage]

If i remember on the newer CPUs the 256 runs at clock speed (on a P3550 the cache runs at 550) on some older P3's and P2's it runs at half clock and older with the cache on the motherboard runs at the bus speed. I beleive the same is true with Celeys as well, i think the 128 runs at clock speed

Please correct me if i'm wrong.

Joe

[wtp]

the 256K L2 cache on the newer ones (coppermines) have full speed running cache, but the old PIIIs, such as the Katmai have 512k running at half the speed. The athlon is worse running at 1/3 the speed.

wtp

[w2nut]

Yup, just went through that, in fact.

The newer ones have the 256 at full processor speed, which is great IF your computational needs don't require swapping in and out larger data sets.

In my case, I found the 650E P3 Coppermine (256K full-speed) to execute a SETI@home work unit in 10.5 hours, whereas my 450 P3 Katmai (512K half-speed) executed in 8 hours, sometimes less. Totally the opposite of what I expected... apparently, between the executable and the data sets, it requires more than 256K and thus will page back and forth to RAM.

That, at least, is the best explanation I have found to date...

w2nut

[falcompsx]

true, but the new cumine cache is more optimized then the old cache, even if it was at the same speed, it's still faster

[neo_otyugh]

it is faster when dealing with chunks of data less than 256k...if you are dealing with chunks of data that are greater than 256k in most cases the katmai will outperform the cumine...if you are gaming the cumine is your chip of choice

[jeepdinger]

i do a little bit of gaming but mostly i do CAD/CAM/FEA. so i'm doing some serious number crunching. sounds like i might want to stick with a PIII 450 w/ 512kb cache. Thanks people, if you have any more information or FYI stuff on the subject i'd appreciate it.

[wtp]

yeah, the older ones can process Seti faster than the new ones.