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Hidden Cores On Phenom CPUs Can Be Unlocked
An anonymous reader writes "One of the major ways a semiconductor manufacturer manages to make the most of its chips is through binning. Chips able to cope with high clock speeds with all cores running end up as premium product lines, while others end up as models rated at lower speed grades, or with fewer cores. In the case of AMD's Phenom CPUs, dual and triple core models are quad cores with some disabled, while some newer quad core CPUs are actually six core models with two disabled. To this end both ASUS and MSI have announced that they have modified versions of AMD 890FX- and 890GX-based motherboards to unlock these hidden cores. Much like overclocking, there is no guarantee that you will gain anything by unlocking the hidden cores — everything depends on just why your CPU ended up in a certain product line."
True, but there's also a good possibility that the your part wasn't binned to fulfill an order. Chips go through a severe set of stress tests that often exceed what will be encountered in practical use. During these tests, it may be revealed that a core doesn't function properly or well enough (it gives bad results) to qualify. All chips go through that, and that's why there's many redundant structures on a chip (to improve yields). (Sony PS3 has 7 SPUs when they build 8 on a chip, Xbox360's got 3 PowerPC cores even though it has 4, Intel disables cache lines and/or functional units, etc. etc. etc.)
So the question is, are those cores disabled because AMD had extra parts and an outstanding order they could fulfill? Or are there actually potential issues that may only be revealed under certain loads? FOr the most part, it just means a game crashes a bit more often than usual (since mission critical servers never do wierd things like this - the money saved isn't worth the potential for extra downtime), or maybe a file gets corrupted. Or worse, your disk gets corrupted.
Plus, AMD's historically been supply-bound and unable to fulfill demand for their product, so there's a potential that instead of getting a binned part, it's actually one that failed their test patterns.
And yes, you see the same behavior with flash chips - NAND flash traditionally ships with bad blocks, and the majority of those can probably be erased and used quite safely (having accidentally destroyed the bad block information before due to buggy software...), but you never can tell why it was marked bad in the first place.
For a while I was selling race car / high performance street car suspension systems.
I had discovered that 90% of the aftermarket shocks being sold as performance upgrades were actually crap. The customer is really not qualified to properly evaluate a shock valving and so it is very difficult for them to differentiate between a proper performance shock and a juiced-up pogo stick.
I started putting shocks on a device called a "shock dyno" (which measures the forces produced by the shock at different shaft speeds) and discovered an absolute parade of horror. Details can be read at http://farnorthracing.com/autocross_secrets6.html
To get the good stuff you needed to be paying upwards of $3000 per corner (so $12000 per car) which is far, far out of the price range of most customers.
So I was building packages based on a brand of shock that was pretty decent and much cheaper. Even though the base design was solid, it still suffered from manufacturing variations. To get around this, I would buy batches and then dyno the lot. Shocks that were close to each other became matched sets, and I'd tweak the adjusters on the shock to ensure each pair was as closely matched as possible. On top of that, I designed some hardware to resolve some other tricky problems typical of the off-the-shelf aftermarket designs, and only used the best bang for the buck components to build them.
When done, I provided a race-quality suspension system, dyno-matched (and it came with the data sheets to prove it) that was very nearly the equal of the $3000/corner systems, for about $500/corner. I say "nearly" the equal because the adjusters on my shocks worked nowhere near as well as the adjusters on the expensive shocks, but in terms of absolute performance, they were effectively identical.
There was almost no markup in these parts; I was hoping to make it up on volume and I knew the customer base was price-sensitive.
These suspensions were INCREDIBLE deals. There was nothing else like it anywhere for anything less than 5 times the price, and unlike all the cheaper stuff, I could prove that it worked. What's more, I could run the cheaper stuff on my dyno and prove that it DIDN'T work; that it was categorically JUNK.
I sold almost none of them, and the universal complaint was "too expensive".
Even when I opened up the books, showed what I was paying for the components, explained why *this* part instead of *that* part, explained every single design decision and proved why it could not be made any cheaper without compromising the functionality, over and over again potential customers would choose to buy non-functional (but shiny) JUNK over functional parts based solely on price.
It was mind-boggling, and eventually I just said to hell with it and found something else to do.
The chip manufacturers are right on the ball here. If I were them, I'd be encouraging the creation of these kinds of motherboards and rather than down-rating the high end parts to make mid/low end, I'd be cherry-picking the best ones for the high end and defaulting the output of my fab runs right to the mid/low end SKUs. In fact, I'd be tempted to DESTROY any chip with a bad core and ensure that all the low-end chips were fully functional - specifically to build a reputation for being "overclocker-friendly".
You can't make money off what you DON'T sell. Believe me, I know.
DG
Want to learn about race cars? Read my Book