More 90nm PowerPC Notes

Discussion in 'MacRumors News Discussion (archive)' started by MacRumors, Jan 8, 2004.

  1. macrumors bot

    MacRumors

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    #1
    A few more notes and confirmation of the 90nm PowerPC 970s...

    This PowerPC G5 Whitepaper (PDF) from Apple has been updated to provide information of the New 90nm PowerPC.

    According to the paper (page 15), the new 90nm PowerPC 970 contains 58 million transitors, uses a 90-nanometer, silicon-on-insulator (SOI) process [not SSOI] and has a die size of 66 square millimeters. The 130-nm 970 PowerPC currently used in the PowerMac G5s have a die size of 121 square millimeters.

    More information of the 90nm PowerPCs should be presented by IBM in February. The new PowerPCs would logically be used in upcoming PowerMac revisions.
     
  2. macrumors newbie

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    #2
    Re: More 90nm PowerPC Notes

    more information about the 90nm process will be presented by ibm today in japan.
     
  3. macrumors 6502

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    #3
  4. macrumors regular

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    #4
    I'm interessted in what the 90 nm 970 wil be called. 970FX seems to be the most likely candidate but an official word from IBM would be nice.
     
  5. macrumors newbie

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    #5
    hi henriok (from appleinsider forums?) ... funny, how small the world is...
     
  6. macrumors newbie

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    #6
    these benchmarks are not worth it. try to use a dual G5 beside a dual xeon and run a few more apps simultanously and you'll know what i mean... the dual G5 is superior ...
     
  7. xid
    macrumors newbie

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    #7
    Of course faster Macs would help, but a far bigger speedup would result from optimizing the applications being used. I've had some code which ran about as fast on a 2GHz G5 than it did on a 1 GHz Athlon. I didn't even bother comparing to a 3GHz Intel. After optimizing, the G5 was about 6 times faster than before. The code wasn't bad, but in this case I had a very tight loop where I multiplied lots of ints with lots of floats and the G5 pays a *huge* penalty for the conversion; Intel/AMD and even the G4 don't. I took that out, inserted some AltiVec on the way... I had to put in some code to check the results because after the initial results I couldn't believe the speed I got and had to make sure I actually did some calculating!

    I don't know what the Benchmarks do, but it seems to rely on two things: bandwidth and serial processing of data streams. Basically this is what a G5 is designed for. If a G5 is not a lot faster for this than any Intel processor, it is a problem with the code and not with the G5.

    A 2.6 GHz G5 would be at most 30% faster and would still lose at a lot of these benchmarks. Better code and the 2GHz would probably be dominating already.

    Cheers
     
  8. macrumors regular

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    #8
    Semi-quote from Halo/Marathon: We're everywhare!! :)
    The Mac world isn't that large after all. Thank god!
     
  9. macrumors 6502a

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    #9
    before the thread is hijacked by those clamoring for a g5 powerbook,
    a few questions:
    does the white paper say anything about heat dissipation?
    what does the change in die-size mean?
    are the new xserves shipping now?
     
  10. macrumors regular

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    #10
    L2 cache

    AFAIK a large part of the Opteron's advatage over the G5 comes from its 1024Kb L2 cache. Does the new 90nm 970 have a 1024Kb L2 cache or have they stuck with the 512?
     
  11. macrumors regular

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    #11
    Since the 90 nm 970 is made up by the same ammount of transistors (58 Million) we can rule out any sigifiant redesign of the chip. Larger cach, integrated memory controller, andvanced power savings and such is out of the question.

    I'd say that the smaller size will be responsible for the chip being cheaper. The processor size is about half of the former, so twice the number of processors can be produced on one wafer, thus reducing cost per processor dramaticly.

    The new Xserves will ship in February.

    The white paper only says that the die shrink results in less heat dissipation but not by how much.
     
  12. macrumors regular

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    #12
    Duh!

    Thanks for the clarification - I should have realised that myself!
    So we will have to wait for the mythical 980 for a larger L2 cache?

    When is the 980 coming - I'm planning on buying a tower this time next year, after the start of yer refresh - will they be 980s by then?
     
  13. macrumors 6502

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    #13
    I totally agree. The numbers on Rob Galbraiths site do also show that the 2 ghz G5 was faster in MacBibble than the 3.06 Xeon machine in the windows version. Unfortunately most software vendors don't seem to care much about the speed of their apps and won't put much effort in optimizing them for the g5 processor. I hope this might change one day, but I don't think it will be anytime soon.
     
  14. macrumors regular

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    #14
    Re: Duh!

    It seems like it. I'm not to surprised. 970 was the first step in the new 900-family and i think it might be somewhat of a working design study; the first step in a long series of processors. Much will be learnt from 970 design, things that will go into future designs.. 980 (or whatever it will be called, my best guess is still 975) will be the first.
    Steve Jobs have promised us G5 processors @ 3 GHz sometime this summer. The 970 is a very unlikey candidate for that feat, so that leaves 980 to fulfill Steves promise.

    I guess that we'll se 980 delivered this fall. If you buy a new tower next spring, you might be into the very nice prospect of buying a dual 3.5 GHz machine :)

    We don't have ANY confirmed information about 980, not even its name. We don't even know it exists at all, that's just something that's very likely. If someone claims to have solid info about 980, you should take it with a handful of salt. At least until IBM and/or Apple says something.
     
  15. Moderator emeritus

    Mr. Anderson

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    #15
    I'll be really interested in seeing what IBM presents, the Apple white paper is more marketing oriented.....

    But it looks good that they've got the 90 nm process going for the XServe. I wonder what the odds are that the top end will be 2.6 GHz - any chances that might be higher?

    D
     
  16. macrumors regular

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    #16
    980/975/whatever

    Dual 3.5Ghz would be sweeeeet.

    Imagine UT2004 running on that.

    Am I right in saying that a doubling of L2 cache would provide a significant performance boost? It all comes from when the P4 went from 256 to 512K cache which seemed to boost performance by >10% clock for clock. So maybe a 15% boost going from 512K tro 1024K?

    This may be a large part of Prescott's increased performance also. i believe it has 1024k L2 cache.
     
  17. macrumors 6502

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    #17
    Re: 980/975/whatever

    I have the feeling that increasing the cache on the 970 might be less effective than on the P4 because the bus speed on the G5 is much higher in comparison to the processor speed.
     
  18. macrumors 65816

    Photorun

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    #18
    Someone pinch me, reading the post and the white paper, is the 90nm 970 actually only HALF the size of the last chip will all the speed? I feel week in the knees.

    Put it in the Powerbook? Heck, put one in an iPod! (kidding).
     
  19. macrumors regular

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    #19
    The increase of L2 cache on previous PPCs show similar performance boosts as the Pentium. The main thing is that cache is expensive. Just look att the Pentium4 EE with 2 MB cache. It is REALLY expensive compared to its little brothere with just 1 MB. Itanium 2-processors with huge caches (6-9 MB) will cost more a piece than a complete dual-G5. I think it's hard to justify verry large caches, but processors will undoubtfully get higher performance with them. 1 MB L2 cache in 980 seems reasonable though. The 750GX got 1 MB so why doesn't 970? It's really a fair question.

    The extremely high bandwidth the 970 and its successors got might be one of the reasons for the farily small cache size and the lack of L3 cache, but it got a terrible overhead so even if it transfers data fast it takes time to initiate a transfer. precious time.

    Concerning the shrinkage of die size. Just do the math:
    130x130 = 16900
    90x90 = 8100
    == half.
    If everything else is the same, which seems to be the case.
     
  20. macrumors member

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    #20
    Room for Growth

    I love how people assume that even with a new die process, the 970 can't even get bumped in speed once. The Pentium4 has gone from like 1.4 ghz to 3.6ghz, and with Prescott will get pushed even further. Do you honestly belive that the 970 has run out of room to grow, even with a new a die process?
     
  21. macrumors regular

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  22. macrumors 68040

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    #22
    Since there is alot of head room in the current processor I suspect the 90nano unit will clock well over 3GHz. It appears that it is more of a question about how hot Steve wants to run the processors.

    Now how well that processor will perform at the higher clock rates is an open question. The lack of a cache size increase does cause concern. One will have to waite for IBM do release all the details. Hopefully they have made some improvements to the processor, it owuld be rather sad if the only thing we got out of this rev is a process shrink and the corresponding faster clock rate.

    Thanks
    Dave


     
  23. macrumors 68040

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    #23
    cost really isn't part of the equation, with the process shrink they could have kept the die size and used the extra space for the extended cache. Sure it would be a problem if you enlarged the die size but this should not happen with the process shrink.

    As you point out IBM alread delivers a low cost processor with a large cache. Granted there are probally difference in implementation but still it is only a cost consideration if the die becomes to large.

    The bandwidth capability of the G5 will mean nothing as the ratio between clock rate and memory pefromance widens. It will widen because even if Apple implements faster RAM it still will not keep up with the 970 as it passes 3GHz.

    Now this may sound like terrible news, but there is the possibility that IBM has attacked the issue in other ways. It is not impossible to improve the performance of the cache. The release of the new documentation from IBM will be very interesting to say the least.

     
  24. Guest

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    Jan 19, 2002
    #24
    Faster PowerMacs soon?

    It was believed that the 130nm 970's would be able to hit 2.6, 2.8 at the highest and to get to 3GHz or more we would have to wait for 90nm 980, which is supposedly due out this fall. Well now that the 90nm 970 is out, who knows maybe we'll see new PowerMacs this month or next pushing 3GHz.

    Think about it... they got a 90nm 970 crammed into a 1U rack. It may only be running at 2GHz because of heat issues. The towers have tons of space for heat sinks and fans allowing them to crank up the speed of the 970.
     
  25. macrumors newbie

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    #25
    I don't know why there not using SSOI! With all the heat the PPC 970 produces, .90 alone won't fix that problem. The Pentium 4 (Prescott) that will be out next month is .90, Intel had to use SSOI in order to deal with the 100+ watt heat problem. The PPC 970 is having the same problem. I would think IBM will have to do this in order for Apple to use the G5 in a notebook.

    I believe SSOI is Intel's patent. IBM may have to get a license to use it.
     

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