Fake PentiumIIs Really DO Exist...
...I should know; I bought one !
updated 03/12/98
use this (win) or this (dos) to check yours
I expect you are all thinking I must have bought the processor from some dodgy bloke in a pub, well no, I got it from a well-established (and as far as I know honest) retailer. They are in fact (as I subsequently discovered) authorised Intel retailers and had no idea what was going on... so what went wrong ?
The device I bought was a boxed Pentium II 300. All the paperwork looked genuine, and the case showed no signs of tampering, however all was not as it seemed. After some weeks of use, a colleague (my boss actually) pointed me in the direction of a german web-zine "c't". The page had some info on some fake PIIs that has been found in circulation over there. I read the page with interest, and was pleased to discover there was a nifty little program that should enable you to check your processor.
Essentially the program checks the level 2 chache supplied in the module; All PIIs of 300MHz and greater should be equipped with ECC (error corrected) L2 chache. Mine wasn't. AAAAAARRRRRGGGGGGHHHH!
I checked with Intel UK's technical support (being an Electronic Engineer does occasionally have its advantages) and they confirmed that every PII of 300MHz or more they have made or will make, is fitted with ECC L2 chache. Indeed some of the portable PII modules of <300MHz also have ECC cache.
After a load of hassle from my supplier, they finally agreed to swap the device (I pointed them in the direction of the c't website, and kept calling them). The processor I now have is OK... why don't you check yours?
"now for the science bit":
Basically the PII is made up of two parts, the CPU, and the cache. The CPUs are all made by the same process - they are essentially identical. Within certain tolerances. This is where the different speed-grades some in. Basically Intel produce processors with varying maximum speeds. As with all processes, they will end up with a gaussian distribution of grades (bell-shaped curve) - so you get say only 10% of processors able to run all the way up to speed A, 80% able to run up to speed B, and 10 % are only able to run up to speed C. (A>B>C).
Those A grade parts are less common & better so they cost more. The B grade parts are the most common. The C grades are rare too, but market forces mean that these must be the cheapest grade - and actually make up the majority of sales. So what do you do ? Easy, you sell a load of B grade parts off badged and guaranteed as C grades. Everyone's happy.
With the PII, Intel must have had some really good yields - they are already selling 400MHz and faster parts. So that probably means that the B grade runs all the way up to 300MHz. In plain English - the majority of recent PIIs will probably run at 300MHz with no problem.
(note to nervous would-be overclockers: there's nothing wrong with running a PII233 at 300 or 333 MHz - the silicon was designed to do it, so it won't catch fire. If you're unlucky, the device will simply be less reliable at these speeds. Oh and running the bus at 100MHz is probably fine for all PIIs as well; BX motherboards are designed to let you do this... I THINK ???!!!... the rest of your PC will hate it though)
So if you're an unscrupulous b@stard, then you buy loads of PII233s, you pay a plastics company a derisory sum to make you a few 1000 exact PII case copies, labled as 300MHz parts, and you rob people blind. Chances are you won't get caught, or even found out !
Intel will probably, one day get round to sorting this out (it's not that hard to give a slab of silicon a section of fuse-link ROM, for instance)... in the meantime, thank you c't.... and TRUST NO ONE.
Simon
_________________________________________________________________________
This page is written and maintained by Simon Nield