The Xbox 360 CPU

The original Xbox used a hybrid mobile Pentium III/Celeron processor, but for the 360 Microsoft went to IBM and got the rights to a PowerPC core.  The move to the PowerPC instruction set meant that there would be no direct binary compatibility with older Xbox titles, but the sacrifice was obviously deemed necessary by Microsoft. 

The CPU itself features three of these PowerPC cores and is currently manufactured on a 90nm process, however Microsoft will most likely be transitioning to 65nm as soon as possible in order to reduce the die size and thus manufacturing costs.  Remember that a die shrink from 90nm down to 65nm will cut the size of the CPU in half, and should be possible for Microsoft sometime before the end of next year. 


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All three cores are identical and feature a 2-issue pipeline and can only execute instructions in-order; we've already discussed the reasoning behind this decision here.  The impact of the in-order execution cores is generally a negative one on current game code, but by going with a much simpler core Microsoft was able to stick three of them on a die with hopes of making up for lost performance by enabling some pretty serious multithreading. 

Not only does the Xbox 360's CPU feature 3 cores, but each core is capable of executing two threads at the same time, making the CPU capable of simultaneously executing 6 threads.  Unfortunately, most titles appear to be only using one or two threads for the majority of their game code, with the remaining threads being used for things like audio encoding/decoding, real-time decompression of game data off of the DVD-ROM and video decoding. 

Microsoft has their own license to use and manufacture the CPU used in the Xbox 360, and thus we see their logo on the chip itself.  Microsoft cools the 3-core CPU using a fairly beefy heatsink outfitted with heatpipes (pictured below): 


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Airflow is supplied by the two rear fans in the Xbox 360; the air is channeled over the GPU and CPU heatsinks using a duct. The larger heatsink on the right is atop the CPU, the smaller heatsink is for the GPU:


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We have previously discussed the Xbox 360's CPU in much greater detail, which you can read about here.

Removing the Heatsinks from the Motherboard The Xbox 360 GPU
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  • preciousstone - Wednesday, May 13, 2009 - link

    this is nice, i found this tutorial via a wholesaler whom is selling this item at very attracting price.

    thanks!
    Reply
  • preciousstone - Wednesday, May 13, 2009 - link

    in case u will need the site address?

    http://www.volumerate.com/details.vr/sku.6116">http://www.volumerate.com/details.vr/sku.6116
    Reply
  • covert0001 - Tuesday, October 14, 2008 - link

    I have just replaced the "x" clamps on a friends board after previously repairing 2 others with 3"rlod".
    I used this method-
    Removed x clamps and heat sinks
    Cleaned dice and sinks thoroughly with methanol and cotton buds
    Put a spot of artic silver on the dice
    Mounted heat sinks with m5 machine screws, nylon washers and washers
    Let the board warm up till the 2 red lights came on and then let it cool
    This method worked a treat on both others
    The problem with this one is it plays a game for about 5-10 minutes then just freezes up. If i switch it off then back on it comes up with the 3 reds again. I can manage to get it to work again but the screen eventually freezes again and 3 reds. Any ideas what could be causing this or to solve this would be greatly appreciated
    Reply
  • steveyoung123456789 - Friday, December 09, 2011 - link

    NO ONE KNOWS WHAT THE FUCK YOUR TALKING ABOUT! Reply
  • xBublizZ - Sunday, April 01, 2012 - link

    I know! Reply
  • JoeMontana1616161616 - Friday, July 05, 2019 - link

    Shut the fuck up and go sit your ass back on the bench, Steve. Reply
  • itsmyfallt - Wednesday, December 14, 2005 - link

    i was going to paint my 360, but dont want to screw over my warranty, is there any way that you can take the outer shell apart and not leave any visible evidence(besides the color change) that you have taken the shell off and tooled around with it? Reply
  • xboxrox - Wednesday, November 23, 2005 - link

    here are a few more details of the insides -

    http://www.teardown.com/press/Port_Xbox_360_PR_112...">http://www.teardown.com/press/Port_Xbox_360_PR_112...

    Reply
  • jugaaru - Friday, November 18, 2005 - link

    I guess the anandtech server is getting hammered, I guess its the first full blown review. Nice work anyway. Reply
  • kmmatney - Thursday, November 17, 2005 - link

    Just google "cpu dice" - I found this quote right away:

    "AMD is not in a position to move its product line to dual-core until it brings on an additional fab--either it's own Fab 36 or a foundry," Kevin Krewell, an analyst for In-Stat and editor of the Microprocessor Report, said Thursday. "Dual core equals two regular CPU dice, so it's not cost effective for AMD to ship dual-core [chips] for the same price as single-core. AMD needs to keep dollars per wafer growing, and aggressive pricing of dual-core would reduce it."

    Looks like many people use to term dice. So for you guys bitching and moaning for Anand to chaneg it - guess what - No Dice!

    Reply

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