The xBox 360 Vs The PS3

The PS3 is a power house. It’s cell processor will kill anything out there now. If you look at the PS3 closly, you will see some faults in it though.

The PS3 has a cell processor that uses a general PPE (Power processor element) 64 bit core with 512 KB system L2 cache at 3.2 GHz and seven SPE (Synergistic Processing Elements) 128 bit cores at 3.2 GHz each. I’m not 100% on how the cell processor works because it is brand new. IBM, Sony and Toshiba have been working on it for some 5 or so years now. From what I understand, the Cell processor’s main core basically delegates it’s calculations to the other 7 cores. Each core is actually designed to “fetch” a job. It asks for a job from the main processor and executes the process and then syncs back up with the PPE (the main processor unit aka Power Processing Element). So you have a huge list of jobs in a large list on the PPE and core units that will take jobs from the main core and process them and tell the PPE that it has done it’s job and it wants a new one. It can even select a certian type of job. This is good and bad. Now you can make 7 SPEs that can do a specific job faster than a general CPU (like the one in your computer now!) can do because it is made to handle that type of code. The bad thing is that if the SPE does not have a process it can do, it will try to do a job it doesn’t know so well and it will take much longer.

The xBox 360 has a different approach to the whole CPU deal. They have a triple core design running at 3.2 GHz on each core with a shared 1MB cache. It is basically like the dual core CPUs with another core for general processor power. I have been saying general processor power in great volume but I never went ahead and told you what it was. Well, a general processor is a processor that can carry out many many tasks while a specific processor (like a graphics processing unit) can carry out a specific task faster and better. Say you have a GPU and you want to try to run a physics calculation or an audio stream through it. The GPU will take much much longer. I’m not going to go into technicals here. If you want to know more about how the general processors work, let me know. Since the general processor is built to handle many types of code, it is ideal for gaming. However, a well built cell processor should be able to crush a system running 3 general processors.

General Processors are better for gaming because games are coded in a combination of integers, floating-point, and vector math with a direct connection to the system cache. Since the PS3′s SPEs (the thing that does most of the work on the processor) don’t have a direct link to the cache, it has to ask for it from the PPE. Dot products are also critical in games because they are used in 3D math to calculate vector lengths, projections, and transformations. The xBox 360 CPU has the dot product instruction per core, where the Cell processor must emulate dot product using multiple instructions.

The PS3 has the RSX graphics chip from Sony and nVidea running at 550MHz. The RSX chip is called the reality synthesizer. The technology was taken from the 6800 GTX chip. It sports a 128-bit memory interface, 1.2 Billion Vertices/sec (this number will affect the MSAA abilities), 136 shader operations/clock with 74.8 billion shader operations/sec and 8 ROPs (Rendering Output Units), with a total of 33 billion dot products/sec all running off 256 MB of GDDR3 RAM. It’s a beast, but I’m sad to say that the xbox 360 has a slightly better GPU.

The 360’s GPU is a custom made processor from ATI. It sports a 128-bit memory interface, 1.6 Billion Vertices/sec, 160 shader operations/clock with 96 billion shader operations/sec and 8 ROPs, with a total of 33.6 billion dot products/sec all running on 512 shared memory on the unified memory bus.

The last thing you want to look at is the memory bandwidth. This will show you how much memory can be shoved through the system. The higher here the better. You want to have more than you need. As your memory bandwidth usage increases, you will see a performance loss even if you have not hit the max amount of bandwidth. The PS3 has 48 GB/sec of total memory bandwidth. 25.6 GB/sec of that coming from the main system RAM and 22.4 GB/sec coming from the Video RAM. The xBox 360 has over five times that of the PS3. 278.4 GB/sec with 22.4 GB/sec coming from the memory interface bus bandwidth, 256 GB/sec coming from the memory bandwidth to EDRAM.

In conclusion, the 360 is a better gaming console than the PS3 because it sports the triple core general purpose processor, it has a better video unit and higher bandwidth. The Triple core general processor has 128 vector registers per hardware thread and one dot product instruction while the PS3′s cell processor’s vector registers are most inside the SPEs themselves. So again, the SPEs will be waiting on the PPE.

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