G4 Tower and Powerbook motherboard question

hardheadhardhead
Posted:
in Current Mac Hardware edited January 2014
First of all, THIS IS NOT A BITCH! I am going to buy a PB, either a 17" or 15". Haven't made up my mind yet...



For the past couple of years Apple has been using 167MHz FSB motherboards in the G4 towers and PB's. Finally the G5's get a "modern" mobo. Although the "cripplin' of the entry level G5 was kinda bush. Nonetheless.



How much of a performance boost would be percievable if Powerbooks came with a (as an example...) 533MHz FSB mobo. This has been standard in high end PC laptops for awhile now. Why has Apple hung on to relatively old mobo technology for so long? As I understand this (the more GEEK among you please correct me if I'm wrong), the PC 2700 RAM can not even be utilized to it's full potential because of mobo constraints. I understand somewhat that there is a mathematical relationship between mobo FSB speeds and RAM speeds.



2x(FSB)167=334.

PC2700 RAM runs at 333MHz.

I'm sure there's more to it than that. A layman's explanation would be welcomed.



In my computer ignorance it just seems to me that Apple's towers and PB's would have an "automatic" speed boost if they would have incorporated a more up to date mobo. In particular the Powerbooks.

Comments

  • Reply 1 of 5
    ghost_user_nameghost_user_name Posts: 22,667member
    First off, Apple is not holding on to "old" motherboard tech. No, the motherboards are hosting an asortment of new tech. It is the CPU that can only support such a FSB, not the motherboard.



    As for the memory comment. You see there is this thing, called DMA, and it grants driect memory access to devices through the chipset. Various items inside your Mac are given this grant, and they benefit from it greatly. Items like your hard drives, graphics card, some PCI cards, ect... they all access the RAM without needing the CPU. So having a DDR connection to your chipset that is well above your FSB connection to your chipset is of use to any and all DMA enabled devices inside your Mac.
  • Reply 2 of 5
    beigeuserbeigeuser Posts: 371member
    Everything that \\/\\/ickes said is true. But I will like to add that the DMA capability is greatly overrated. The only component which could possibly take advantage of the DDR is the CPU (which can only access RAM at SDR speeds). The other devices (graphics cards, hard drives etc.) do not access the main RAM enough to show any significant difference.



    Bare Feats did several tests a while ago and discovered that the 167MHz Bus/DDR RAM combination will show a 9-13% increase in performance only when a Cinema 4D render is performed while transferring 3.6 GB over a Gigabit ethernet network. In less demanding situations, the performance increase was close to 0%.



    Here's a link: http://www.barefeats.com/pmddr5.html
  • Reply 3 of 5
    ghost_user_nameghost_user_name Posts: 22,667member
    Just noting that DDR RAM is less expensive then SDR RAM, and in the long run will help with future upgrades...
  • Reply 4 of 5
    hardheadhardhead Posts: 644member
    Ahhh, so it comes back (somewhat...) to Moto's processors being unable to take advantage of faster mobo's.



    barefeats.com is excellent. Even for a non-geek like myself.
  • Reply 5 of 5
    bartobarto Posts: 2,246member
    Quote:

    Originally posted by BeigeUser

    The only component which could possibly take advantage of the DDR is the CPU (which can only access RAM at SDR speeds). The other devices (graphics cards, hard drives etc.) do not access the main RAM enough to show any significant difference.



    With Quartz Extreme, I am very sceptical of that. Very, very sceptical.



    Anyway, a G4 with a faster FSB would be kickass, unfortunately it's not going to happen.



    Barto
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