> The Abit BP6 was legendary with enthusiasts because it let them make a dual CPU system with cheap Celeron CPUs.
And 2 celerons were cheaper than a CPU with double the performance?
And 2 celerons were cheaper than a CPU with double the performance?
Celeron CPUs were usually CPUs that shared the same core architecture as the current Pentium standard, but often had a lower core clock speed, lower core memory speed, and/or had smaller L2 caches.
Workloads have different constraints however, and simply doubling cache, clock speed, or memory bandwidth doesn't necessarily double performance, especially when running more than one application at once. Keep in mind, this is Windows 98 /NT/2000 era here.
Symmetric multi-processing (SMP) could be of huge benefit however, far more than simple doubling any of the above factors. Running two threads at once was unheard of on the desktop. These were usually reserved for higher-binned parts, like full-fledged Pentium workstations and Xeons (usually the latter.) But Abit's board gave users a taste of that capability on a comparative budget. Were two cheaper than a single fast CPU? Probably not in all cases (depends on speeds). But Abit's board gave users an option in between a single fast Pentium and a orders of magnitude more professional workstation: A pair of cheaper CPUs for desktop SMP. And that was in reach of more people.
In short, two Celerons were probably more expensive than a single fast Pentium, but having SMP meant being able to run certain workloads faster or more workloads at once at a time when any other SMP system would have cost tons.
But in the real world, the perceived performance improvement was more than doubling. The responsiveness of your machine might seem 10 or 100x improved, because suddenly that blocking process is no longer blocking the new process you're trying to launch, or your user interface, or whatever.
It's much rarer to see misbehaving multithreaded processes hog all of the cores. Perhaps most processes are not robustly multithreaded, even in 2025. Or perhaps multithreading is a sufficiently complex engineering barrier that highly parallelized processes rarely misbehave, since they are developed to a higher standard.
Except on Windows laptops. Where, although the computer is idle, your favourite svchost.exe will heat your system and trigger thermal trottling.
This had an interesting side effect: Celerons of that era overclocked extremely well (stable 300 -> 500MHz+), due to the smaller and simpler on-die L2 cache relative to the Pentiums of the era, whose L2 cache was much larger but had to be off-die (and less amenable to overclocking) as a result.
An overclocked dual Celeron could easily outperform the highest-end Pentiums of the era on clock-sensitive, cache-insensitive applications, especially those designed to take advantage of parallelism.
You could attempt to head toward ~700 but I never could keep it stable there.
Another thing that helped the Celeron overclocking craze is Intel seemed to damage the brand badly out of the gate. The original Celerons had no cache at all, performed terribly and took a beating in PC reviews. So even though the A variants were much better this still had a stink on them.
The thing that probably helped the Celeron the most with overclocking though was they gimped them by only giving them a 66mhz front side bus speed. Since you had to increase this number to push the locked multiplier CPU speed up this was an advantage if you were going to overclock as you could buy a capable motherboard and run it at stable 100mhz. Whereas you'd have a lot more system wide problems trying to push a Pentium's 100mhz bus higher.
2x Celeron 366 MHz @ $123 each - https://en.wikipedia.org/wiki/List_of_Intel_Celeron_processo...
1x Pentium III 733 MHz @ $776 - https://en.wikipedia.org/wiki/List_of_Intel_Pentium_III_proc...
And that's assuming that performance scales linearly with clock frequency (which it doesn't).
That would be quite the "budget" SMP build. The 366MHz "Mendocino" was based on the prior Pentium II core I believe. So quite the disparity in single-threaded workloads.
These were competing with PII processors in 1998, and for folks who wanted to go dual CPU it was the way to go.
There was a whole cottage industry of folks modding these CPUs as a small side hustle for people who were not comfortable with soldering onto CPU pins if you wanted to put these into a SMP system.
Performance really did mostly scale linearly with clock speed back then - but for a single CPU. The dual CPU setups were not nearly as efficient due to software not being as multi-threaded as it is today. The big win were folks with two monitors (rare!) who could run apps on their second monitor while playing games on the first. Typically you would only see frame-rate increases with CPU clock - and of course the very start of the serious 3D accelerator (3dfx, nvidia, ATI) scene back then.
It was certainly the golden age of enthusiast computing - especially for gaming.
When Intel switched from Slot 1 to Socket 370, there was a market for "slocket" adapters that allowed Slot 1 motherboards to take Socket 370 CPUs. The best of these adapters worked out a way to re-enable SMP on Celerons by tweaking the pin layout to disable the lock Intel had added. What made the BP6 so popular is that it was a native dual-slot Socket 370 motherboard that had this modification built in so it could use unmodified dual Celerons out of the box.
> Performance really did mostly scale linearly with clock speed back then - but for a single CPU. The dual CPU setups were not nearly as efficient due to software not being as multi-threaded as it is today. The big win were folks with two monitors (rare!) who could run apps on their second monitor while playing games on the first. Typically you would only see frame-rate increases with CPU clock - and of course the very start of the serious 3D accelerator (3dfx, nvidia, ATI) scene back then.
Even if you only had one monitor, multitasking was FAR better on a dual-CPU machine than on a single CPU system. For example, if you were extracting a ZIP file, one CPU would get pegged at 100% but the system was still responsive due to the second CPU not having any utilization. If you use a dual-Celeron BP6 system, it's a much nicer and more modern feeling experience than using a single-PII system even with the faster CPU with more cache.
I ran Slackware on my BP6 while I was in college. Of course CONFIG_SMP wasn't set in the default kernel config at the time so you had to build your own. Great for running bind, apache, sendmail, etc., and of course NetQuake servers. :)
I bought two to have one gaming machine and one coding/hacking machine (including learning about networking now that I had two computers). Geek heaven.
Yes but they got hard to find in a hurry once word spread. I had two 366s in my BP6 overclocked to 550 but IIRC I had to buy a few to find two that were stable at this frequency.
> There was a whole cottage industry of folks modding these CPUs as a small side hustle for people who were not comfortable with soldering onto CPU pins if you wanted to put these into a SMP system.
No modifications necessary with the BP6.
> Socket 370 era Celeron processors had a Pentium II core, but Intel disabled the ability to change the multiplier to discourage overclocking
The whole point, really. Sorry, but you are.
In the Pentium / PII era, CPU speed was the product of 2 factors: front side bus speed and clock multiplier.
The original P5 and the 2nd gen P54 ran at FSB speed: 60 MHz or 66 MHz.
The later Pentiums ran at an integer multiple:
Pentium 120 = 60 MHz * 2 P 133 = 66 * 2
The PII ran at larger multipliers. I bought a PII 450 MHz on a Gigabyte motherboard that fit in my Baby-AT case, rather than the then-common ATX case.
450 = 100 MHz FSB * 4.5
That cost.
Slower PIIs had a much slower 66 MHz FSB.
PII 300 = 66 * 4.5
The Celeron had a locked multiplier but you could change the FSB.
So, take a 300 MHz chip (running at a locked 4.5x the FSB) but put it on a much faster 100 MHz FSB at the same multiplier and you got a 450 MHz chip, and because it had a much smaller but on-die L2 cache, it was more likely to be stable.
These Celerons came on a Slot 1 convertor and that needed to be modified to enable SMP operation.
Pics:
https://www.vogonswiki.com/index.php/Intel_Celeron_300A
The famous BP6 motherboard ignored that setting and forced the uniprocessor-only Celeron to run in dual processor and overclocked it as well.
So for 2 budget sub-£150 CPUs, rated for 300 MHz on a sluggish 66MHz FSB and one CPU only, you got a dual-processor 100MHz FSB machine with the raw single-core performance of something like a £500 processor.
I never had one but you bet I heard about them and strongly considered it.
People pretty routinely nearly doubled the clocks on Celeron 300As, anyway. :)
Celerons were consumer-grade budget kit.