i dont get this - "front side bus"

Discussion in 'Mac Basics and Help' started by DisFrikkenWill, Jul 11, 2005.

  1. DisFrikkenWill macrumors member

    Jun 14, 2005
    this has to do with the single processor powermac g5's

    ok the 1.6 has 800mhz front side bus
    and the 1.8 has 600mhz front side bus

    what is this? some people say the 1.6 is better and some people tell me the 1.8 is better. im getting confused. i think the 1.8 is better because its 1.8???
  2. risc macrumors 68030


    Jul 23, 2004
    Melbourne, Australia
    The original 1.6 and 1.8 GHz single processor Power Mac G5s have 1/2 the processor speed as the FSB as do all of the dual Power Macs, but the new single 1.8 GHz single processor G5 is more like the iMac G5 with it's 1/3 FSB. Personally I'd go with the newer 1.8 over the older 1.6 but thats just me.
  3. wangahrah macrumors newbie

    Feb 22, 2001
    In the "simplest" analogy, the front side bus is how the computer components "talk" to each other. The faster the fsb, the better. But the 1.8 G5 will be faster than the 1.6, even though the bus is a little slower. The logic board on the single 1.8 is a little crippled, with the bus slowed from 900mhz to 600mhz, but it doesn't matter a huge deal.

    Heck, my G4 has a 166mhz bus and still feels fast.
  4. ~Shard~ macrumors P6


    Jun 4, 2003
    The FSB is the means by which the main components of the computer talk to each other - it's a data pipe/bus. As with everything, faster is better, but it isn't the only consideration. As for the processor speeds themselves, yes, a 1.8 G5 can process instructions faster than a 1.6 G5, but it is limited by the FSB - you could have a 4.7 GHz G5 but it won't perform too well if it's operating on a 100 MHz FSB. ;) (That isn't possible anyway, but just using an extreme example...)
  5. iomar macrumors 6502

    Dec 28, 2001
    Los Angeles, CA
    Actually I don't know much about FSB also. What does it do exactly? Why would apple put slower FSB on 1.8 faster processor? and faster FSB on slower 1.6 processor?

    I have always been in the dark when people were talking about FSB. I would appreciate clarification.

  6. mklos macrumors 68000


    Dec 4, 2002
    My house!

    You have to remember that the single 1.8 GHz PowerMac G5 was a $1499 Machine. So its a scaled down version of the PowerMac, which is the reason why its cheaper.

    The frontside bus, is the main bus between the processor(s) and the RAM. The faster the FSB, the faster the data can move from the CPU to the RAM.

    The FSB on dual processor PowerMacs is capable of running at half the processor speed. So the Dual 2.7 GHz PowerMac G5 has (2) 1.35 GHz FSB's, one per processor.

    The iMac has a FSB that runs at 1/3rd the speed of the processor even though its capable of running at 1/2 the processor speed. I imagine Apple does this to keep the heat down as running the FSB at half the CPU speed creates a tremendous amount of heat on the system controller.

    The FSB on any Mac running a G4 processor is only capable of running at 167MHz, which is way slower than a G5 processor's FSB. This is the main bottleneck with a G4 processor. If the G4 would support something like a 400 MHz FSB, it would be a very good processor to keep in something like a MacMini, or iBook.

    A G3 processor will only support either a 66MHz, or 100 MHz, and possibly a 133MHz FSB.

    I hope this clears things up on a Front Side Bus (FSB).....

    If not, then ask more questions!!!
  7. ~Shard~ macrumors P6


    Jun 4, 2003
    Wikipedia is always a good resource! :cool:

    As I stated above, the FSB basically connects your CPU to your HD, RAM, PCI devices, etc. So, your processor can compute as fast as it wants, however if it can't relay that data to the other parts of the computer which require it in a timely matter, it's a rather moot point. As a result, the FSB can often be the bottleneck of a system.

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