sliderider is correct 😉
*In general, POD83 has the best FPU, but runs at only 83Mhz @ stock. Don't confuse this one with the Intel Overdrive! That processor is "exactly" the same as the standard Intel 486DX class CPU's, and come with 16kb WT cache. There are Intel DX4's with WB cache, but those are still much slower (in FPU performance) then the Intel Pentium Overdrive. The POD83 can sometimes be overclocked to 100Mhz, but even that is an overclock many won't be able to reach.
One problem with overclocking POD is that you can't raise the voltage as it already runs at 5v from the motherboard
*Cyrix 5x86 (not to be confused with Cyrix DX4!!) comes next, being only slower FPU then the POD but running at 100Mhz. There are 2 faster models inexistance, a 120Mhz part (which is scarce, but not impossible to find) and a 133Mhz part (which is nearly im-pos-si-ble to find!).
Best bet is to get a 100Mhz part and try to overclock. Even though the Cyrix 5x86 is known to not overclock well, one Vogoner here has managed to get his 100Mhz part booting at a very respectable 150Mhz!
Also Cyrix 5x86 has some extra options that can be enabled which make Cyrix 5x86 even faster, but those options don't always work.
feipoa is kinda our local Cyrix 5x86 specialist, if you need any info about them it would be a good idea to ask him 😉
He seems to know more about these chips then the Cyrix folks themselves did 😜
*The AMD 5x86 is basically just an AMD DX4, but it is the best AMD DX4-class CPU as it is clocked higher (133Mhz instead of just 100). Extra note:AMD DX4 comes in no less then 3 varieties, and this has to do with the internal cache. There are models with 8kb WT (Write Through), models with 8kb WB (Write Back) and 16kb WB cache. All AMD 5x86's come with 16kb WB cache and all are clocked at 133Mhz. There are 2 faster models available for the AMD 5x86, a 150Mhz part and a 160Mhz part, but both are impossible to find.
I'd suggest to not shell out money for these 150/160 parts as the 133Mhz models are easy overclockers! Especially as you can raise it's voltage 😉
The AMD 5x86 has by far the slowest FPU of the 3, but also has the highest clock rate which (at least partially) make good it's relatively slow FPU. 160Mhz should be obtainable with, say, 50% of these chips?
Some will even run at 200Mhz! But this is rather a crap shoot, most won't run that speed
Confusing, isn't it? 😉
So, Socket 3 FPU in a nutshell and from best to worst:
Intel Pentium Overdrive @ 83Mhz is best (even better if you overclock to 100Mhz, which many can't do though)
Cyrix 5x86 (the faster the better). The 100Mhz are by far the easiest to find, but don't overclock too well (usually).
AMD 5x86 is by far the easiest to find! Just yesterday one was being sold on cpu-world for a mere €4! They have the slowest FPU but do have that slow FPU run at the highest speed of the 3. 133Mhz is standard and 160Mhz is regarded as a realistic overclock with 200Mhz being a possibility
Edit:Of course if you for whatever reason can't manage to find any of these 3 chips, then you could try getting one of those Socket 3 upgrade chip, like the Kingston Turbochip or an Evergreen, but those will not overclock as good as regular AMD 5x86.
Then theres the DX4's, of which exists a LOT of varieties
Edit2:To answer your questions directly:
nemesis wrote:I have a few questions myself along this line.
1. Would a 5x86 have a noticable advantage running a 3d card vs any 486?
Yes, as all 486-marked CPU's run at either 100Mhz or slower (except for one particular AMD DX4-120 chip). All AMD 5x86's run faster then any 486 and All Cyrix 5x86 are faster then any 486 at the same clock
nemesis wrote:2. If yes, then wouldn't a Cyrix 5x86 have a better run than an AMD 5x86? (Iirc, Cyrix was closer to a pentium 1 than AMD).
Cyrix 5x86 > AMD 5x86, but only at the same clock rate.
Commonly, Cyrix 5x86 is 100Mhz while AMD 5x86 will be 133 (as a general rule of thumb).
