Someone please explain Memory to me in overclocking terms

[Phalanx]

Hi, i'm thinking of getting a Athlon - m 2500 and i really don't know what memory has to do with overclocking, what does PC3200 differ from PC2700? and why are some different kinds of memory more expenisve than other, Crucial Ballistix to crucial value?
What does CAS mean?

thx

[mike_w]

The processor speed is calculated by the FSB times the multiplier. While the multiplier only affects the CPU, the FSB affects the CPU and memory. In Athlon XP systems, you generally want the RAM speed to be the same as the CPU FSB. As such, you want the FSB higher first, then the mulitplier as high as possible.

For example, when the FSB is 200 and multiplier is 10 (so that the CPU speed is 2000mhz), it will be faster than when the FSB is 100 and the multiplier is 20, even though the CPU clock speed is the same.

PC3200 is 200mhz (400DDR), while PC2700 is 166mhz (333 DDR). The higher the speed of the memory, the faster you can run the FSB. The PCxxxx speed is roughly the DDR speed times 8.

CAS latency is normally 2, 2.5 or 3. At stock settings, it only makes about 5% difference (if that), but it might be worth it if you spent loads of money on the rest of your system, but I personally don't think the extra money is worth the small performance increase. Perhaps more important is the fact that PC3200 with a lower CAS will probably be able to overclock to a higher speed.

[Phalanx]

so, if you have PC3200 memory, you can only raise the FSB to 200?

[Shogun]

You can push it higher, but it's not 100% certain that it will go higher,

[Phalanx]

so if I wanted to raise the FSB, would I need that PC 4000 memory then?

[mike_w]

so, if you have PC3200 memory, you can only raise the FSB to 200?

You're only guaranteed to reach PC3200 speeds - you can try overclocking, but there's not telling how high you might be able to go - but if you have expensive RAM with tight (i.e. low) timings (one of which is CAS), you are probably going to be able to overclock better than cheap RAM with loose timings.

[mike_w]

so if I wanted to raise the FSB, would I need that PC 4000 memory then?

That should gurantee that your memory can hit 250mhz, but it would also depend on motherboard and CPU.

[Phalanx]

So, what memory would you recomend? i've found some PC4000 512mb Balistix for £82 which sounds pretty good, if I got a Mobile XP 2500, that would surely give it a good boost, what are the default FSB and Multiplier on this chip?

[Shogun]

I don't know if this has been said but with ram if you want to up the FSB and it's not stable you can always slacken the Cas timings a bit which should allow you to up the FSB.

[mahoodlum]

The 2500 xp m isn't often recognised by desktop mobo's so it defaults to lowest settings - 600mhz Mobile XPs are renowned for their overclockability. I believe they are 166mhz FSB chips - but not certain (and not much fussed if they are or aren't cos i'm never going to run it at stock speed!)
Mine's at 209 FSB x 11 multiplier, 1.7v - so it clocks at 2300mhz. My Ram is cruicial value PC3200 and the system is relatively stable.
I'm having a problem i think with my Graphics card RAM - think it's getting too hot

[SStuntman]

i have a Athlon XP 2500+, with some 512mbs 3700 OCZ RAM which i know is overkill since my FSB isnt very high and i found that i cant overclock it much because my graphics card becomes unstable and crashes my comp, if only i had a AGP/PCI lockable motherboard i reakon i would beable to overclock it loads with my Volcano CPU fan.

Hope this helps

[Shogun]

i have a Athlon XP 2500+, with some 512mbs 3700 OCZ RAM which i know is overkill since my FSB isnt very high and i found that i cant overclock it much because my graphics card becomes unstable and crashes my comp, if only i had a AGP/PCI lockable motherboard i reakon i would beable to overclock it loads with my Volcano CPU fan.

Hope this helps

How do you mean unstable? Overheats or just crashes? Also does it corrupt before it crashes?

[jonathan_phang]

Hey there, I guess you are wondering whether or not to buy special ram so that you can use the full potential of your XP-M 2500. Thats exactly what i did before and i went for 3500 Kingston ram, which would let me have a moderate 16mhz oc. And tbh it didnt really add that much performance.

At the moment, in my nf7-s, i have my ram at 200FSB with 12.5 mutlipler and it is pretty solid at 2.5 ghz. i'm sure i can go more, but i dont have time to mess with and test all the settings & voltages (since i finished being a student!) so thats fine with me. Bottom line is, if youre not to much of an expert and dont want to waste a lot of time, jsut go for crucial 400. Its stable and generally quick - and they have a lifetime warranty.

But as ever, the choice is up to you

[SStuntman]

How do you mean unstable? Overheats or just crashes? Also does it corrupt before it crashes?

yeah sorry, it corrupts meaning the screen is covered in artifacts it doesnt crash or get too hot, although i have to reset the computer and put back my settings.

Athlon 2500+(FSB 166) if i go over FSB 180 graphics card becomes unstable
MSI KT400 Ultra
1GB RAM
Radeon 9800 np
onboard sound
Windows XP Home SP2