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  1. #1

    different RAMs in the market

    Hi

    After some research, i found out that there are quite a few different technologies for ram. i'll be appreciative if anyone can give me any specific details on each, if possible.

    RDRAM
    SDRAM
    DDR-SDRAM(DDRAM)

    In particular, i found out that RDRAM have a speed of 800MHz, SDRAM at 100MHz and DDRAM at 200MHz.

    However, it seems, at least in my region, DDRAM is much more popular than RDRAM, which is supposingly to be faster.

    Other than price, is there other factors making RDRAM less ideal than DDRAM? Also, other than lack of demand, what factors are keeping the price high?


  2. #2
    DDRAM is the newest technology and faster. The speed of RAM matters in overall performance. If its slow it will be a bottleneck. I'm not sure if newer motherboards are even still compatible with the older stuff but it shouldn't be used either way. If it's an older machine that you just want to upgrade you may need the older SD. Basically motherboards are designed for a certain type of RAM. This should dictate your decision.

  3. #3
    Join Date
    Feb 2004
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    772
    hi uncle mad,

    Typical SDRAM can transfer data at speeds up to 133 MHz, while standard RDRAM can crank it up over 1 GHz. Though some motherboards can use RDRAM as system memory, it is so fast, most boards cannot fully benefit from the speed. Because of this, RDRAM is typically used for video memory on graphics acclerator cards, for cache memory (located on the CPU), and for system memory in high-performance workstations and servers.

    An improvement to RDRAM called Direct Rambus (DRDRAM) allows for even faster data transfer rates. DRDRAM uses a 16-bit bus rather than the 8-bit bus DRAM uses, which means it can handle 8 operations at once and can transfer data at a speeds of 1.6 GHz. Now that's fast.

    A very interesting RAM type is the DDR RAM, which is expected to hit the market in 2001.

    DDR stands here for Double Data Rate. It is a technology that transmits data on both sides of a tact signal.

    This way the performance has been doubled; a 133 MHz SDRAM chip can very easy become altered to a 266 MHz DDR chip:

    DDR doubles up the data transmission using both sides of a clock signal

    It should be pretty easy for the market to change for DDR RAM. The modules look like and operate quite similar to existing SDRAMs. We just need new chipsets to start the migration.

    for more details plz check out the link...
    -----------------------------------------------------------

    http://www.hardwarecentral.com/hardw...views/1787/6/.

    thanks
    Bright Info Solutions

  4. #4
    Join Date
    Feb 2005
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    RDRAM = rambus = mostly dead technology in the PC market.

    SDRAM is 'old' at this point. Modern chipsets have moved on to DDR/DDR2

    The outright speed of rdram is not the only concern, if I remember right, ranbus had fairly crappy latency which with large amounts of memory could produce noticeable slowdowns. There was also price when rambus was new it was very expensive, and intel and rambus had made a deal that lots of people didnt like.

    Ah. http://en.wikipedia.org/wiki/RDRAM is a pretty good overiview.

  5. #5
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    The bus width of RDRAM is narrower than DDR, and so the 800Mhz rating does not make it any faster than DDR. I'm not aware of any current motherboards that actually use RDRAM... it was popular for a little bit a few years ago, and then got eclipsed by DDR.

    SDRAM is a general category that includes DDR SDRAM, and PC100/PC133 SDRAM. If you see something that doesn't mention DDR, it's likely PC100 or PC133. It's not used anymore either.

    DDR is the only way to go (I've never heard it called DDRAM... just call it DDR, or DDR SDRAM if you like) these days.
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  6. #6
    That was a very useful reply.

    However, i've got further questions.

    I found out that there's a new variation of DDR, which is DDR2. This new variation has a clock rate of 400Mhz and up.

    Also, i've read that DDR2 cannot be slot into DDR"1"'s memory slot.

    However, i only know there's DIMM, SIMM and RIMM. DDR is being placed in the DIMM, now that DDR2 do not fit into those of DDR's slots, does that means there's other variation of IMM for DDR2? Or simply, it's DIMM2? Or have i read from a invalid article?

    Whenever we purchase memory sticks or see their specifications, we'll notice there'll be e.g. Kingston DDR400 512MB. Sometimes, there's a CL2.5 or CL3 which pops up behind. What does this CL represent? How many different variation of CL is there?

    Thanks so much.

  7. #7
    Join Date
    Feb 2005
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    CL is cas latency, you can get more info here http://www.dewassoc.com/performance/...as_latency.htm or you can google for another link.

    DDR2 is still a DIMM, its just a different pinout so you cant use DDR2 in a DDR1 slot by mistake (it wouldnt work). SIMM's had to be installed in pairs, DIMM's can be single (this will depend on exact specs of memory/motherboard combinations mind you).

  8. #8
    Thanks for your fast reply.

    Since DDR2 and DDR1 are both using DIMM, then what do you mean by putting it into a DDR1 slot by mistake? Also, you mentioned about the different pinout, what kind of pinout is this? And do we have to make any adjustment to use DDR2?

    Thanks.

  9. #9
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    Originally posted by Uncle Mad
    Thanks for your fast reply.

    Since DDR2 and DDR1 are both using DIMM, then what do you mean by putting it into a DDR1 slot by mistake? Also, you mentioned about the different pinout, what kind of pinout is this? And do we have to make any adjustment to use DDR2?

    Thanks.
    DIMM isn't a specific pinout or packaging configuration, it simply means that the pins on each side of the memory are independent from the corresponding pins on the other side of the memory, which is not the case on SIMM-based RAM.

  10. #10
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    While we're at it, I was hoping someone could explain the difference between Unbuffered and Registered?

    And ECC or not ECC?

    Thanks
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  11. #11
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    Originally posted by ccole
    While we're at it, I was hoping someone could explain the difference between Unbuffered and Registered?

    And ECC or not ECC?

    Thanks
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  12. #12
    DDR2 is a 240 pin module
    DDR is a 184 pin module

    You need to install them in pairs always, otherwise they may not work.

  13. #13
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    No, DDR and DDR2 do not need to be installed in pairs, however - modern motherboards do allow you to installed 'matched pairs' of ram to improve speed.

    This is caled 'dual channel', and my AMD64 board supports it (using 2 non-matched sticks!).

  14. #14
    That's nice.

    Does that means that both DDR and DDR2 can be sloted into a DIMM, while the former is 184 pins and the latter is 240 pins, we'll have to be sure of the number of pins supported by the DIMM slots before we buy our memory module? So DIMM has both 184 and 240 pins in it's slots, as an industry standard(e.g. different lengths of DIMMs to suit different length-caused by pins, of DDRs)?

    So that's the definition of dual channel. Is there any disadvantages of using dual channel?

    More here. When i buy server boards, they always talk and 2 channels or 4 channels. Any relation?

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