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  1. #1
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    SiS650 memory upgrade

    I'm hoping to upgrade a friend's computer. She has Intel Pentium 4 Chipset > SiS650 which is running 256MB SDRAM. The specs state:

    Integrated High Performance DDR SDRAM Controller
    - Up to 3 DIMMs of DDR266/PC133
    - Maximum 3GB System Memory

    I'm wondering how a 1GB DDR2 667 or 800MHz module would be expected to perform (or otherwise).

    Alan

  2. #2
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    Re: SiS650 memory upgrade

    Alan,
    First let me say that I have little recent experience on the Intel platform.

    First thought: DDR2 doesn't work with this chip. DDR2 is not backward compatible to DDR, in many different ways: DDR2 are 240-pin modules, DDR are 184-pin modules; the "notch" isn't in the same place (even though I would say that that is the smallest "problem" <img src=/S/smile.gif border=0 alt=smile width=15 height=15>; they operate on different voltage (DDR2 1.8 V, DDR 2.5 V), not to mention that it is clocked twice the bus speed etc. So I wouldn't expect such modules to perform anything. <img src=/S/sad.gif border=0 alt=sad width=15 height=15>

    In short SiS introduced it years ago: “Sep. 2001 Introduced SiS650, the world's first Pentium®4 chipset with integrated 256-bit 2D/3D graphics". DDR2 came along 2003/2004 (and support on the AMD platform 2006).

    Additional info:
    As you say “Integrated High Performance DDR SDRAM Controller”. At most it is capable of handling DDRs; they were quite new around then.

    The PC133 is even older but existed for some years after 2000. SDR (Single Data Rate) SDRAM usually were 100 and 133 MHz (or 66 MHz) and were referred to as PC100 and PC133, same speed for everything. A PC133 was a 168-pin DIMM and 3.3 V, if I remember correct.

    The DDR SDRAM, is the so common, until DDR2 (DDR3) came along. DDR is Double Data Rate. In the mentioned example, DDR266, also called PC2100, it is a 266 MHz & 133 MHz "combo". 184-pin.

    DDR2, faster, initially longer access times, but now lower latencies, as you know very common these days. The examples you mention for DDR2 are also called PC2-5300 (667/333) and PC2-6400 (800/400), but they must have a chipset with the speed and support for DDR2 etc.

    A perhaps not so typical(?) Pentium 4 board with the chipset (650) was the EliteGroup P4S5MG which had the following specs. PC2100, PC1600, PC100, PC133, i.e. it supported 2 DDR + 2 SDR. But that explain the "DDR266/PC133" you mention, two types of memories supported on the same 133 MHz, that now are old. The PC2100 is probably possible to get, but the other one is harder. But I guess most boards with the chip, at the time, only used the DDR.

    You mention the chipset, and that is one important piece, but as we know the motherboard can have other limitations as well, lower maximum RAM installed etc. But the speed should follow the max cap. of the chip. What's the mobo?

  3. #3
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    Re: SiS650 memory upgrade

    I suspect the short answer is then "no go". <img src=/S/grin.gif border=0 alt=grin width=15 height=15>
    I ran SIW on the system and it comes up with this:

    Motherboard

    <table border=0><td>Property </td><td>Value </td><td>Manufacturer </td><td>NEC COMPUTERS INTERNATIONAL </td><td>Model </td><td>SiS650 </td><td>Version </td><td>1.0 </td><td>Chipset Vendor </td><td>Silicon Integrated Systems (SiS) </td><td>Chipset Model </td><td>SiS650 CPU to PCI Bridge </td><td>South Bridge </td><td>SiS 961/962 </td><td>CPU </td><td>Intel Celeron </td><td>Cpu Socket </td><td>Socket 478 [Slot-1 ] </td><td>Processor Upgrade </td><td>Slot 1 </td><td>Max CPU Speed </td><td>3000 MHz </td><td>System Slots </td><td>3 PCI, 1 AGP </td><td>OnBoard devices </td><td>Ethernet (Disabled) </td><td>RealTek LAN </td><td>Memory Summary </td><td>Maximum Memory Module </td><td>Size 1024 MBytes </td><td>Maximum Capacity </td><td>2048 MBytes </td><td>Memory Slots </td><td>2 </td><td>Name </td><td>Physical Memory Array </td><td>Warning! Accuracy of DMI data cannot be guaranteed </td></table>

    From what you've said, its upgradability with newer parts is not very hopeful.

    Alan

  4. #4
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    Re: SiS650 memory upgrade

    "I suspect the short answer is then "no go"."

    Yes. <img src=/S/grin.gif border=0 alt=grin width=15 height=15>



    Anyway, since you mentioned NEC, a quick search and I found someone asking about memory for a similar system a year ago. BTW I didn't ask, but it is a desktop, isn't it? (I don't read Yahooo!!, and the answers at the end are a little off, 8 GB. <img src=/S/grin.gif border=0 alt=grin width=15 height=15>)

    Since no machine name, product line, I can't say much more but: to look for DDR memories (if the board isn't using SDR PC133 only). Within the DDR standard they are backward compatible as you know. So if one has a DDR PC2700 (DDR333), or a PC3200 (DDR400), it should work on a DDR266 system. But some motherboards can be a bit cranky as we know (and perhaps more so, if they were of the first DDR boards around).

    SiS press release: SiS Launches SiS650. But I've learned not to trust everything, since the chip is used by a motherboard vendor and then things may change.

    Your first post was about the chip support, two memory types, but your scan shows only two slots, so either SDR or DDR, and a guess would be DDR. But that must be confirmed too. I think it's not a problem to find suitable DDR memories (So I would not say "not very hopeful"). Worse, as mentioned, with the PC133. The DDRs, however, may be of a faster type, but compatible. As you say 1024 MB per module, max 2048 MB single-channel, so why not a 1024 stick, but the right sort. Or if one have them around: two 512 MB.

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