PC100 or PC133

Can I use PC100 memory with a Duron 700? Would it be a lot better to use PC133 cuz I already have PC100. If I want more PC100 do I need to get the same brand as I already have or can I get any brand? Does the CAS matter?
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More about pc100 pc133
  1. Yes, for AMD processors you need PC133 and CAS2 SDRAM.
  2. you do NOT need PC133 ram with the Duron proc. You can use either pc100 or pc133 ram. The current socket a mobo's allow you to choose to run the meemory clock at 100 or 133.

    for instance i'm running my abit kt7 board with pc133 ram. There is a choice in the softmenuIII bios that allows me to choose to run the memory at HSTCLOCK(which is the FSB at 100mhz) or HSTCLOCK+PCICLK(which is the fsb+the pci bus clock, total = 133).

    The pci clock is 1/3 the hostclock. so if you up the FSB(for overclocking) you will also be upping the PCI clock.
    My FSB=112 so my pci clock is 37.333 so when i set my memeory clcok to HSTCLK+PCICLK you get 149mhz.

    anyway.. you pc100 is fine, and i would sugesst buying an identical brand if you choose to upgrade the amount of ram you have. You may want to test the memory you have first, just in case it doesn't work(name brand ram shouldn't be an issue, just the generic stuff sometimes fails) you dont want to have two sticks of unusable ram.

    Abit KT7 RAID
    Duron 650@896
    128MB pc133@149cas2
    Antect s1030/sblive+
  3. You are wrong! Sure the motherboard supports it, of course it does, but, if you read the requirements for AMD Athlon/Thunderbird/Duron processors you need at PC133 CAS2!!!
  4. I have been using my duron with 100mhz ram with no probs.
  5. Durons have 100mhz EXTERNAL FSB, PC100 or PC133 will work fine. But it seems that the standard of the RAM also matters.

    Please visit <b><A HREF="http://zidane222.cjb.net" target="_new">http://zidane222.cjb.net</A></b>
  6. My Athlon 700mhz runs fine with PC100 memory. I've built plenty of Duron systems with PC100 memory and no problems. But, it would make more sense to spend 10 extra bucks (or whatever the margin is) to get a little more speed out of PC133. You can even mix the 2, which makes NO sense. But hey, at least u have options.

    -MP Jesse
  7. What does PC133 do that PC100 can't?
  8. Hi everyone,
    I'm not an expert on this matter, but if you have PC133MHzSDRAM and IF YOU RUN IT at 133MHz, then your info TRANSFER rate is a 33% greater, since it runs 33% faster than PC100 RAM.
    Another thing is latency times, CAS is about this (correct me anyone if I'm wrong) and the lower the better.
    CAS has to do with access to info times, so a lower CAS means quicker access to info stored in your RAM, and higher Mhz (say 133, 150, 2x133=266 soon to come DDR or whatever) means faster transfers of that info.

    I said IF YOU RUN IT at 133MHz, becouse you can have PC133 running at 100Mhz or even 66Mhz (like today's underexploited celerons do). What it is to say, an underclocked stick of PCRAM will work fine at lower speeds than those of its specs (or I think at least it should) but you don't know how well it will work overclocked (that's about generic or brand, but that's another thread..).
    Also, I've seen PC133 cheaper than PC100 lately so it makes sense to buy 133 since you can use it at lower speeds and think of safe memory OC or later upgrades.

    Saludos a todos
  9. Goes 33% faster
  10. MrGomez

    You're right but at the moment, you will probably not be able to run an atlon at much over 100Mhz DDR FSB as the chipsets don't allow it but buying PC133 ram definitely makes sense
  11. How can I find out whether the SDRAM that I'm using is 100 odr 133 mhz??
    I need to know, because I want to add SDRAM
  12. I was under the impression that the memory controller in the VIA chipsets allowed the use of either?


    one of the first UK T-Bird users....
  13. You can mix them but they will only run as fast as the slowest Dimm, I would buy 133 mem as it gives you scope for future upgrades...


    one of the first UK T-Bird users....
  14. ok, Here's some basic definitions:

    PC133 = 133mhz bus (SDRAM stick is certified to run at UP TO 133mhz)

    PC100 = 100mhz bus (SDRAM stick is certified to run at UP TO 100mhz)

    CAS3 & CAS2 (I won't go into detail, but cas2 is faster than cas3, but also more expensive)

    A Duron Processor (or AMD Athlon Thunderbird as well) can use either a 100mhz or a 133mhz RAM BUS (in spec). This means it's totally up to you which you run, but strongly reccomend the 133mhz bus as it is much faster. Please note this is the bus speed of the RAM, the processor will always run at 100mhz DDR (200mhz effective) in spec.

    Summary: if you have pc133 ram, you can run it at either 100mhz or 133mhz, but pc100 ram will only run at 100mhz (in spec). If you have pc100 already, it will be cheaper to just buy more pc100 and run both the new and the old ram at once at 100mhz. It may be smarter to sell your old pc100 ram, and replace it all with pc133 ram, and run it at 133mhz (faster).

    To find what speed RAM you have right now, you can either read the sticks themselves (they will probably have it printed on them), or check your BIOS. If your BIOS says "hstclk" you are running a 100mhz memory bus (meaning you probably have pc100), if it says "hstclk+pci" you have a 133mhz memory bus (meaning you have pc133 memory).

    Please note this was written excluding PC66 and lower memory. This is because although technically supported by the VIA chipset, it isn't a reasonable solution.

    If you have any other questions, feel free to ask me at either of the addresses below.

    Scott Newton
    AIM: Scootin159
  15. With the new duron mobos you may be using hstclock (only 100Mhz) while having PC133 SDRAM stuck in your machine, that depends on mobo and on how good is the bios setting.

    As scootin159 said, the best way is to look the RAM it self. Many times it has a code printed in the chip, and the last digit (that's my case) tells specs in nanoseconds.
    133Mhz means 133 millions cycles in a second, so each cycle takes 7,5 nanoseconds to complete for a 133MHz SDRAM running at 133MHz. If you see 7,5 ns then your RAM is suposed to reach 133 MHz.
    Read this article: http://www.hardocp.com/articles/memory/sdram1page2.html

    smn198, Dravic in this thread has 112FSB in a Duron. I know it's unlikely to get to 112 on actual socket A chipsets, but you know your chances are MUCH greater with 133. 112 for 100SDRAM, is out of its specs; it is not for 133RAM.
    Well....OK, 12 Mhz beeing very optimistic may be quite crappy for some...but...you know it is not for OClockers, and even more with todays multipliers.
    Anyway as we agreed, best choice right now is 133.

    Bytheway will 760 chipset support SDRAM?

    Saludos a todos
  16. I understand that of course 133 Mhz certified mems are better than 100 Mhz certified mems but do you know where i could find a benchmark that would show the overall increase in performance on a Via 133. I'm quiet sure that the overall perf wo'nt increase by 33% ...
  17. Here's a look at one person's results:

    <A HREF="http://www.exampc.com/ram1-1.htm" target="_new">http://www.exampc.com/ram1-1.htm</A>

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