PC 2700 vs PC 2100

Discussion in 'Buying Tips, Advice and Discussion (archive)' started by BIGgui_X_, Oct 15, 2003.

  1. BIGgui_X_ macrumors member

    Sep 5, 2003
    I have a question about RAM speed, and how it exactly work. I'll receive my new dual 1.25 G4 this week, with only 256MB ram. I know they say that i need pc 2700 RAM in it. My question is : Can i put PC 2100 in it ? i'ts 266 mhz instead of 333. If i do that, is it the RAM that will try to clock up to 333 or is it the ram bus that will clock down to 266 ? I aldready tried to put some pc100 in a 133 slot, it worked fine. Since the system bus of the dual is 167 mhz, does it make any différence if i try to put pc 2100 in 2700 slot ? I dont mind buying pc 2700 if it makes any différence, but, since i saw deals like 512 MB pc 2100 for 79 $ canadian, I said to myself that it would be a good idea to ask the question.. Thanks
  2. Zeke macrumors 6502

    Oct 5, 2002
    Greenville, SC
    You want to use the PC2700. Otherwise the bus is slowed down to the slowest RAM. It's also DDR so the RAM speed is double what your bus speed is. So going from 333 Mhz (double your bus speed) down to 266 Mhz is effectively making your system bus 133 Mhz. Not what you want to do...buy the good stuff.
  3. BIGgui_X_ thread starter macrumors member

    Sep 5, 2003
    ok, and i suppose that if I slow down the bus to 133 and that the CPU vs BUS ratio is fixed somewhere in a ROM, i'll slow down the CPU speed too ? Thanks
  4. sparky76 macrumors regular

    Jul 2, 2003
    Your machine may try to run the 2100 at 2700 speeds, possibly damaging the RAM and the Mac. Can't see Apple honouring any warranty in that case. Best to buy the faster RAM
  5. Vilacr macrumors regular

    Feb 4, 2002
    The ram will effectively clock down to the slower piece of ram. It will not harm your system, only slow it down. Instead of the ram running at 333 mhz it will run at 266 mhz.
  6. Greenlightboi macrumors newbie

    Jan 21, 2003
    Oh come on guys this is basic upgrade knowledge... here is the real story. Anything lower then the bus speed wont work... the mother board doesnt magically slow it self down. Slower speed ram simply will not function. higher speeds are clocked down to the motherboards default. so u need to use PC 2700 (DDR333 I believe) or higher
  7. fraeone macrumors regular


    Sep 26, 2003
    Seattle, WA
  8. FuzzyBallz macrumors 6502a


    May 2, 2003
    Home of Al-Qaida
    Are you two serious? What's this? Dumb and dumber?

    1st of all, it's a stupid idea to even consider cheaping out on RAM on the thread starter's part. 2nd, the thread starter already tried some PC2100 and it worked. 3rd, if you want better performance (CPU and RAM in sync), just get a pair Samsung PC2700 512MB, instead of mixing PC2100 and PC2700.
  9. BIGgui_X_ thread starter macrumors member

    Sep 5, 2003
    I never tryed pc2100 in 2700 slot, i tryed pc 100 on a 133 board (older Mac) and thanks for the opinion concerning my stupidity. I was asking a question about how RAm is clocked in a computer. I just wanted to know if the RAM will try to clock up, or will the Bus slow down instead. Thanks to the one that answered my questions. A chance that i'm french canadian and that i dont have alot of dirty english words in my vocabulary.

  10. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    If the ROM is programmed and the computer checks it, it should disable that stick of memory.

    Worse if the computer does not check the memory ROM, then it'll try to run the memory at the faster speed.

    If it's cheap memory, it may work (sort of) at the faster speed, but be unreliable. This could lead to memory corruption, HD corruption as this faulty stuff saved back to the HD, or lots of kernal panics.
  11. BIGgui_X_ thread starter macrumors member

    Sep 5, 2003
    now THAT is an answer !!
    thanks everybody !
  12. yamabushi macrumors 65816


    Oct 6, 2003
    It is possible to intentionally overclock RAM if you use very high quality RAM. As Sun Baked said, this can cause instability. Corsair offers some modules that can be safely overclocked.http://www.corsairmemory.com/
    I don't know of any way to safely change memory settings on Macs, but it is possible on some PC systems to go beyond reccomended specs. Anyways, you will get the best value and performance from buying good quality RAM that your system is designed to run. You will also avoid potential speed, reliability, and warranty problems. Get some PC2700 from Samsung or Crucial.
  13. Greenlightboi macrumors newbie

    Jan 21, 2003

    Oh yes FuzzyBallz, cause u must have a clue....


    As far as putting the 100 in a 133 slot, it may have overclocked it self, which, is a VERY bad idea. Ram is hit or miss, but to be *safe* you should run with the minimum the board requires. I also dont blame the thread starter for trying to save money... computers are an expensive thing to maintain..

    So you've been bitched, don't post if your gonna be negative :rolleyes:

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