Can you mix pc133 and pc100 sdram?

Discussion in 'General Hardware' started by Digerati, Jan 28, 2003.

  1. Digerati

    Digerati Guest

    I am running a GVC ar862 motherboard with a duron 750 and was just wondering if using one stick of pc133 ram and once stick of pc100 ram would negatively affect system stability or performance.

    There are only 2 memory slots and the board specs say it can accept either pc100 or pc133 sdram. I happen to have one stick of each and was just wondering if i could use them both at once.

    I don't care if it would make the pc133 ram run at 100mhz or whatever. Just as long as it ran stable I'd be cool with it.

    Anyone know?

    thanks
     
  2. rettahc

    rettahc Guest

    yeah it should work the 133 will slow 100 tho
     
  3. stevem2k3

    stevem2k3 Guest

    My moms has pc133 and pc100 mixed and runs fine
     
  4. NetRyder

    NetRyder Tech Junkie Folding Team

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    Yup, works fine.
     
  5. scriptasylum

    scriptasylum Moderator

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    Hold on a minute...

    The current run of PC133 memory out there recently can NOT run in PC100 mode.

    I had bought some PC133 about 6 months back for an older Celeron system that used PC100 and it worked, but then a friend with the same basic PC bought PC133 about 1-2 months ago from the same retailer and it didn't work. A call to the place of purchase told him that you have to get the memory you need now and run the memory at the speed specified (this does not include slight overclocks though). He was able to take it back to get the right memory and it has worked fine ever since.

    I'm not sure when (or why) this changed, but you might want to make sure before you buy. Just ask the salesperson so you are covered if there IS a problem and have to take it back.

    Again, this is only for newer memory. If you have access to older PC133 memory, then yes, it should run fine.
     
  6. TechSupport

    TechSupport Guest

    i have looked into this a bit in the past. I found that double sided pc133 works at 100mhz, but single sided (the latest type) does not... might be worth asking about it first...

    although if the motherboard specifies that it will support a cpu at 133mhz bus speed, then it should take any type of pc133 whether it be single or double sided.

    the majority of older celeron motherboards will run at a max of 112MHz bus, so PC133 cannot run at PC133 if needed... hence it wont work with the newer types. At work, we have some duron based systems which run single sided pc133 which didnt work in a p3 600mhz slot1 motherboard (440zx chipset i think it was)... even though the duron runs at 100fsb
     
  7. maz4ruth

    maz4ruth Guest

    Just put it in, if it boots up, then you're cool! ;)
     
  8. Shamus MacNoob

    Shamus MacNoob Moderator Political User

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    The idea here is in the #1 slot you place the pc100mhz and the pc133mhz in the second in the bios the setting should be set to auto detect for the ram speed ... and this will set all the slots to the same value as the first ..... as for the fsb speed that has nothing to do with the speed of the ram that is two different things all together
     
  9. scriptasylum

    scriptasylum Moderator

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    That's the trouble, newer PC133 will not run at PC100 speeds. It has just changed recently though, so older memory (>6months) should be fine running PC100.
     
  10. Shamus MacNoob

    Shamus MacNoob Moderator Political User

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    We never heard if it worked or not LOL

    seems he said he had the sticks in hand!!

    Oh well as for the new ram sticks not running at 100mhz I cant see what changes they have made to older pc133 ram ( now) after this much time why would companies spend any amount of time or effort into changing the specs of something that is all ready outdated as is?? pure logic says that 100mhz will pass through a stick that can handle 133mhz ..... but 133mhz will fry a stick that was made with a max of 100mhz ..... unless there is some new law and some company spent time and money to remodle pc133 ram sticks I am gonna bet that you got a bad stick and that the same law's apply.... some machines (older) cant handle the pc133mhz sticksand some machines can ...its a hit and miss you put it in and either it works or wont ....but if you have access to the bios and the ram settings ... chances are that you are gonna get 100mgz to pass through something made to handle more... like a cpu your logic says that you cant send less mhz into a cpu that was made to handle more ..

    But I am sure that the law of electricty has not changed in the last 2 monthes ... and that no company is spending money on changing old tech ram sticks when all they have been doing is spewing out those sticks for years as is....
     
  11. scriptasylum

    scriptasylum Moderator

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    Hey, I agree with you and I'm not trying to argue either. I am going by what the packaging of the newer memory, salesperson, and experience tells me. The system that was getting the new memory is a Compaq and as you know, there aren't a whole lot of settings the user can adjust. The PC just wouldn't work until he got the "right" memory. BTW: I believe the brand of memory he got was PNY (at Bestbuy).

    Like I said before, if Digerti has older sticks in hand, it's a moot point since they most likely will work fine.

    No, it doesn't make sense for memory manufacturers to change something that already works and is outdated anyway. And I agree, the laws of electricity haven't changed either. Maybe it is as TechSupport said: older PC133 is double-sided while the newer PC133 is single-sided. That would mean they are putting more mem in every IC, which could be the problem.

    Again, I'm not trying to argue, just trying to answer Digerti. If I'm wrong, I'll be the first to admit it. ;)
     
  12. Shamus MacNoob

    Shamus MacNoob Moderator Political User

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    Yes and ditto was more of an open topic really not trying to put you down in any way shape or form ...... the one sided ram could be the culprit in your case ..... on Ebay there is tons of ram all backwards compatible for all those that might need to grab some pc100 pc133 and even god forbid pc66 ......



    :)