I have a question about the number of cores. Usually, we have 2, 4, 8 etc. which is 2^n. But here there are only 15 cores( 2^4 - 1), can anyone point out any special reason of doing this?
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mburman
@yingchal Good question! This bothered me in the past as well. To answer it, the GTX 480 does ship with 16 cores. One of its cores is disabled however. From what I can tell, the reason is poor yield - the number of chips that actually worked. Instead of tossing out a chip with one malfunctioning core, it made financial sense for NVDIA to simply ship the chip with that core disabled. They probably disabled one core on every chip to maintain consistency.
(Not really course-related but does answer the question) Another common reason: NVIDIA was planning a rather easy upgrade of their product line by enabling more cores. Both Intel and NVIDIA use this trick very often. For example, in NVIDIA's current product line, GTX660, GTX670 and GTX680 all use the same GK104 chip, but GTX680 has most cores enabled.
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Xiao
Extra Fun Stuff:
A while back, the Phenom II tri-core cpu from AMD became well known because you can easily unlock its 4th core (who produces only 3 cores anyways :P). In fact here is the DIY video. Since then manufacturers realized the power of hardware geeks and started using more tamper-proof mechanisms to disable those hidden cores. Some "apparent" techniques involve laser cutting the core out or even damaging them so they cannot be used.
If you could unlock open the extra cores of a GTX660, your name would most likely be heralded in the walls of reddit for weeks or even months :)
Happy hardware hacking!
This comment was marked helpful 3 times.
sfackler
The same thing happened with ATI's HD 6950. It is identical to the HD 6970, with 128 of the 1536 unified shading units disabled. People figured out that you can just flash the 6970's BIOS onto a 6950 and turn the units back on (unless they were actually fried in the first place).
I have a question about the number of cores. Usually, we have 2, 4, 8 etc. which is 2^n. But here there are only 15 cores( 2^4 - 1), can anyone point out any special reason of doing this?
This comment was marked helpful 0 times.
@yingchal Good question! This bothered me in the past as well. To answer it, the GTX 480 does ship with 16 cores. One of its cores is disabled however. From what I can tell, the reason is poor yield - the number of chips that actually worked. Instead of tossing out a chip with one malfunctioning core, it made financial sense for NVDIA to simply ship the chip with that core disabled. They probably disabled one core on every chip to maintain consistency.
More about yield: Why NVDIA cut back the GTX480
This comment was marked helpful 2 times.
(Not really course-related but does answer the question) Another common reason: NVIDIA was planning a rather easy upgrade of their product line by enabling more cores. Both Intel and NVIDIA use this trick very often. For example, in NVIDIA's current product line, GTX660, GTX670 and GTX680 all use the same GK104 chip, but GTX680 has most cores enabled.
This comment was marked helpful 0 times.
Extra Fun Stuff: A while back, the Phenom II tri-core cpu from AMD became well known because you can easily unlock its 4th core (who produces only 3 cores anyways :P). In fact here is the DIY video. Since then manufacturers realized the power of hardware geeks and started using more tamper-proof mechanisms to disable those hidden cores. Some "apparent" techniques involve laser cutting the core out or even damaging them so they cannot be used.
If you could unlock open the extra cores of a GTX660, your name would most likely be heralded in the walls of reddit for weeks or even months :)
Happy hardware hacking!
This comment was marked helpful 3 times.
The same thing happened with ATI's HD 6950. It is identical to the HD 6970, with 128 of the 1536 unified shading units disabled. People figured out that you can just flash the 6970's BIOS onto a 6950 and turn the units back on (unless they were actually fried in the first place).
This comment was marked helpful 0 times.