Mixing Cas 3 with Cas 2 memory!?

[GIJersey]

I am curious as to what happens when you mix Cas2 with Cas3 sticks? I had a system running with a 128M 100mhz Cas3 and a 128M 133Mhz Cas2. I really didn't notice any anomilies with the system other than an ocasional blue screen.

Are there certain syntoms that occur in this configuration?


Thanks

Mark

 

[AndyHui]

Please read the FAQ: RAM Considerations: mixing CAS2 and CAS3 RAM.

 

[Paragon1]

According to the FAQ's here at this site, the memory will only run as fast as your slowest stick. Unless you go into the bios and force it to all run at CL 2, which would basicly overclock your CL 3 stick.

edit FAQ man beat me to it In other words, and i'm sure the next 10 people that reply to this thread will let you know , read the FAQs

 

[GIJersey]

Thanks for the fast and very informative replies Andy and Para! Another thing I want to know about is the settings in the BIOS for Ram. Mine is currently set to "By SPD" (which I have no idea what it means?) there are other choices also like 7ns at 146mhz and so on... I am assuming that the "By SPD" is the default setting? Which is the correct setting for 128M 133Mhz Cas 2 Sticks?

One other thing, I have a 3 year old ASUS P2B Mobo and the manual say's supports PC100 SDRAM. What will happen if you put PC133 SDRAM on this Mobo? Will they run at 133mhz?

btw: Is there a way to speed up the AGP slot mhz speed?

Thanks for all the help! You guys ROCK!

Mark

 

[AppleTalking]

"By SPD" means that the motherboard will attempt to read the SPD ("speed") information on the memory module and then configure the bus speed and CAS latency correctly. I think that the correct setting for those chips would be 7.5ns at 133MHz., but I could be wrong. (And if I am, someone please correct me ). If you leave it at the "By SPD" setting, both your memory chips will be running at 133MHz., CAS 3 latency.

If you put PC133 RAM in that Asus motherboard, it will run at 100MHz. unless you start overclocking the FSB (Front Side Bus) speed, in which case it will run at whatever you can manage to overclock it to.

As for the AGP slot speed, some motherboards have an AGP divider setting. Raising the divider setting (that is, bringing it closer to 1/1) would dramatically overclock your AGP slot, possibly causing system lockups and hardware errors. The only other way to increase your AGP speed is to overclock the FSB, since that changes the bus speed from which the AGP speed is derived. Take this example:

With a 100MHz. bus speed and a 2/3 AGP divider, your AGP slot is running at 66.66MHz.
If you increase your bus speed to 110MHz., keeping the same AGP divider, your AGP slot is now running at (110*2/3) = 73.33MHz.

Good luck!
Nick

 

[Leokor]

<< I really didn't notice any anomilies with the system other than an ocasional blue screen. >>


You call that "no anomalies"? I would become genuinely concerned and start debugging your hardware setup. A quick search through the knowledge databases on the particular stop error codes you're getting should give you an idea on where to start.

Leo

 

[GIJersey]

Apple, Thanks for that very detailed explaination! It's Appreciated!

I am looking at the manaul for this ASUS P2B Mobo and I notice that the setting for the"CPU Core:BUS Frequency Multiple" Is this what you are talking about in order to overclock the FSB? It is currently set to 100.2Mhz. I am running a PIII 550 with factory fan. The other settings that are available are (103Mhz, 112Mhz, and 133Mhz) Which one would you reccomend I try and also is the possiblity of damaging the system a factor with setting this too high?

I gather from what you aid that if I overclock the FSB I can get more out of the 133Mhz CAS 2 memory sticks that I have installed in this 100Mhz Mobo? Will they run at 133Mhz with the FSB overclocked? As well speeding up my AGP slot and possibly my hard drive access?

Thanks for the help!

Mark