The Worst CPUs Ever Made (2021)

As a system builder for a "custom computer shop" back in 1997/98, I came here just to make sure Cyrix was on the list.

Funnily, I feel like SIMD instructions are slowly reinventing what the itanium did out of the box.

I think a modern compiler could likely do a good job with itanium now-a-days. However, when it first came out, there simply wasn't the ability to keep those instruction batches full. Compiler tech was too far behind to work well with the hardware.

I would vote for the Pentium IV for all the reasons mentioned in the article, but more importantly because it was initially coupled with Rambus memory. Intel pushed that tech so hard to try and squeeze out AMD. Super high frequency, high bandwidth, high expense memory with terrible latency was not the future anyone wanted. Intel's hubris back then was off the charts.

I know intel wanted Itanium to succeed for the same reasons, but the PIV came very close to home since it actually shipped for consumers. Oddly enough, Extreme Tech was a huge shill for Intel back in those days. Funny they don't mention that in this article.

> Itanium held the idea that we could accurately predict ILP at compile time (when the halting problem clearly states that we cannot).

I don't know where these notions are coming from.

Compilers can (and do) reorder instructions to extract as much parallelism as possible. Further, SIMD has forced most compilers down a path of figuring out how to parallelize, at the instruction level, the processing of data.

Further, most CPUs now-a-days are doing instruction reordering to try and extract as much instruction level parallelism out as possible.

Figuring out what instructions can be run in parallel is a data dependency problem, one that compilers have been solving for years.

Side note: the instruction reordering actually poses a problem for parallel code. Language writers and compiler writers have to be extra careful about putting up "fences" to make sure a read or write isn't happening outside a critical section when it shouldn't be.

Man, that 6x86 CPU is still getting the short end of the stick nearly three decades later despite being a pretty solid chip.

So, first it generally had a higher IPC than anything else available (ignoring the P6). So, the smart marketing people at cyrix decided they were going to sell it based on a PR rating which was the average performance on a number of benchmarks vs a similar pentium. AKA a Cyrix PR166 (clocked at 133Mhz) was roughly the same perf as a 166Mhz pentium. Now had they actually been selling it for a MSRP similar to a pentium 166 that might have seemed a bit shady, but they were selling it closer to the price of a pentium 75/90.

Then along comes quake which is hand optimized for the pentium's U/V pipeline architecture and happens to use floating point too. And since a number of people had pointed out the Cx86's floating point perf was closer in "PR" ratings to its actual clock speed suddenly you have a chip performing at much less than its PR rating, and certain people then proceeded to bring up the fact that it was more like a 90Mhz pentium in quake than a 166Mhz pentium (something i'm sure made, say intel, really happy) at every chance they get.

So, yah here we are 20 years later putting a chip with what was generally a higher IPC than its competitors on a "shit" list mostly because of one benchmark. While hopefully all being aware that these shenanigins continue to this day, a certain company will be more than happy to cherry pick a benchmark and talk up their product while ignoring all the benchmarks that make it look worse.

Now as far as motherboard compatibility, that was true to a certain extent if you didn't bother to assure your motherboard was certified for the higher bus rates required by the cyrix, and the other being it tended to require more sustained current than the intels the motherboards were initially designed for. So, yah the large print said "compatible with socket7" the fine print later added that they needed to be qualified, and the whole thing paved the way for the super socket7 specs which AMD made use of. And of course lots of people didn't put large enough heatsink/fans on them which they needed to be stable.

So, people are shitting on a product that gets a bad rep because they were mostly ignorant of what we have all come to accept as normal business when your talking about differing micro architectural implementations.

PS: Proud owner of a 6x86 that cost me about the same as a pentium 75, and not once do I think it actually performed worse than that, while for the most part (compiling code, and running everything else including Unreal) it was significantly better than my roommates pentium75.