End user questions about Altivec, 64-bit optimization

Discussion in 'General Mac Discussion' started by MegaSignal, Jul 1, 2004.

  1. MegaSignal macrumors 6502

    Joined:
    Oct 20, 2003
    #1
    As merely an end user, I need someone (brainiacks, coders, et al) to help explain to me whether or not certain applications will work any faster with a G5 as opposed to a G4 - namely Final Cut Express, iDVD, and iMovie.

    Pardon my paraphrasing here, but I've heard that these applications have simply removed Altivec in order to make them work more efficiently with the newer 64-bit G5s.

    Bottom line: Will these apps work faster on a G5 (Dual 2.0) as opposed to a G4 (Dual 1.25)? Is there a difference within these apps depending on what computer they're used on?

    Thanks in advance as always!
     
  2. ltgator333 macrumors member

    Joined:
    Jul 6, 2003
    Location:
    Albion, MI
    #2

    first off, being these are apps that will REALLY benifit from Altivec, I doubt Apple would take support for Altivec out, the G5 chip does have Altivec, the same Altivec as the original G4's (MPC 7400). Making the app 64-bit aware would not hinder it's ability to use Altivec. Bottom line, the G5 can do everything the G4 can do and it's memory bus is considerably faster.. unless $ is an issue the dual 1.25G4 would be a waste
     
  3. Daveman Deluxe macrumors 68000

    Daveman Deluxe

    Joined:
    Jun 17, 2003
    Location:
    Corvallis, Oregon
    #3
    Well, from a technical standpoint, the AltiVec unit in the G5 isn't as efficient as it is in the G4e as a result of the unit's placement on the die. Two extra clock cycles were added so that data can get from the front end to the VMX unit--the VMX unit is so far away that the signal can't propagate across the chip in one clock cycle. However, the G5's AltiVec performance is roughly equal to that of the G4e due to the increased clock speed and the much more efficient branch prediction unit.
     
  4. ltgator333 macrumors member

    Joined:
    Jul 6, 2003
    Location:
    Albion, MI
    #4

    yep.. that and G4e has the Altivec enhanced... it was somthing I was really hoping IBM would reverse engineer and add to PPC 970fx, it's unclear whether or not that will happen though. The only other thing about G4e that was nice is.. oh yeah nothing LOL...
     
  5. daveg5 macrumors 6502a

    Joined:
    Nov 28, 2001
    #5
    The dual 2MBL3 cache was nice and made up somewhat for it's slower bus, could you imagine how fast a dual G5 2.5 would be if it had dual 2MB L3 caches running at full speed no less, wow!.
    Also the 7 pipelines compared to 20+ on the G5, the G5 needs that buss speed cause when it has to start over it has 20+ pipes to go through, could you imagine a G5 with just 7 pipes, that would be insanely fast and instant,
    I believe it had lower power demands then the G5, so you wouldn't need all of those fans, better altivec implementation. and caching implementation.
    but the slow bus and slow memory really hurt it, even so it is as fast as a G5 on a clock to clock basis on non bus/ intensive things, and the 4 pipeline 7410 G4 is faster than both with it 1MB L2 cache clock to clock speed.
    Stupid Motorola never increased the buss/memory and motherboard i/o to G5 standards or finished the 64 bit version, competition would have been great like AMD and Intel. so until the Imac G5 arrives 90% of Apple sales are still G4's.
     
  6. MegaSignal thread starter macrumors 6502

    Joined:
    Oct 20, 2003
    #6
    Thanks

    Don't know if my reply made it or not...

    ...if not, thanks again - very informative discussion! :)
     

Share This Page