Well, for starters, I'm still trying to understand why the Pluto is faster than both the Thunderbird and the Coppermine.

Because Thunderbird wasn't direct upgrade over Pluto/Orion, it was mostly cost reduction for OEM and future Socket A release.

750 Mhz Pluto has 512 Kb 300 Mhz L2 cache working via internal 64-bit bus.
700 Mhz Thunderbird has 256 Kb 700 Mhz L2 cache working via internal 64-bit bus.

So that's only 2.3x times faster at the cost of halving cache size. And let's also not forget that K7 has gigantic exclusive (doesn't copy data into L2) 128 Kb L1 cache, so faster but smaller L2 cache aren't necessarily the better one.
Compared to that, Coppermine increased L2 bandwidth 8x times, over Katmai core, by going full speed cache with 256-bit internal bus.

Yes, indeed, those are valid points. Still, it surprised me, I was sure that a full speed on-die cache would translate to better real world performance. Obviously, that isn't the case.

Athlons had insane floating point performance, and well, games kinda liked that. 😀

The Slot A build now has a brother (with an identical case): yet another Slot 1 PC 😀
Fun fact: through a series of unforeseen events, my wife ended up building 99% of this PC (and this is actually the first PC she ever built entirely by herself) - she even did basic wire management (which... looks better than mine) 😁.
The only thing I did was to mod the USB front panel connector, to make it compatible with the MB connector.
Yep, it's official... 2020 is weird.

Thank you to @aaronkatrini for the GeForce 2 Pro 😀

THE SPECS:
CPU: Intel Pentium 3 Coppermine 1 GHz FSB133
Motherboard: Gigabyte GA-BX2000+
RAM: 512 MB PC133 @ CL2
VGA 1: Asus V7700PRO/32M (nVIDIA GeForce 2 Pro 32 MB) + custom cooler
VGA 2: Righteous Orchid 3D II (3dfx Voodoo 2 12 MB)
SOUND: Yamaha YMF724F-V + SB-Link cable (one of my favorite sound cards, somehow I always end up using it for most Win98 builds where DOS is also an option)
HDD: Hitachi 82 GB
OS: Windows 98 SE

Some pics:

Did you have Super Bypass enabled? That makes quite big difference.

https://www.anandtech.com/show/474/14

I came here to pretty much ask the same thing.

As for the different Athlon CPUs, you could also try "overclocking" the Pluto via the 0 ohm resistor locations on the CPU.

I bet if you take the heat spreader off, you will find that you actually have an 800 or 850 core and the L2 cache could probably be bumped up as well.

It has been a few years, but if I remember right, some of the 750s even came with 900Mhz CPU cores.

I know about Super Bypass, however the Gigabyte GA-7IXE does not have a BIOS option to toggle it on/off. Anyway, based on the benchmark results that I got, I assumed that it's probably enabled by default, but I will look further into this when I play with one of the boards again.
I remember from back in the day that there were also some Windows utilities that could enable Super Bypass.

Regarding overclocking, I only tried FSB overclocking (112MHz x 7.5), and it worked without a hitch. However, soon I will have a Goldfinger device, which will allow me to really push these CPUs to their limits 😀 And I'm actually curious if the Thunderbirds will start outperforming the Plutos after a certain clock speed has been surpassed.
Once I have new data I will update this thread.

bloodem wrote on 2020-10-12, 14:53:

Well, this is very strange, I did not expect this at all! The Thunderbird is actually slower (even when overclocked) than the Pluto. Whaaaaa?!

Heh, I remember being similarly surprised back in the day when I got my first Socket A system with a Thunderbird 750. Ended up being slightly slower than some Slot A based Athlons. It was a weird time. But then again, I wasn't as proficient at tweaking memory timings and such back then, and I think I only had PC100 sticks.

bloodem wrote on 2020-11-02, 20:05:

SOUND: Yamaha YMF724F-V + SB-Link cable (one of my favorite sound cards, somehow I always end up using it for most Win98 builds where DOS is also an option)

Yeah, the YMF7x4 cards are incredibly versatile. No other PCI sound card can provide the same feature set, without being paired with something else.

On that note, I recently replaced my generic YMF724 with a Guillemot Maxi Sound Fortissimo which uses higher quality components and also has Digital Out (TOSLINK). It's amazing how much sound clarity one can get out of DOS games using that.

Joseph_Joestar wrote on 2021-03-23, 09:47:

Heh, I remember being similarly surprised back in the day when I got my first Socket A system with a Thunderbird 750. Ended up being slightly slower than some Slot A based Athlons. It was a weird time. But then again, I wasn't as proficient at tweaking memory timings and such back then, and I think I only had PC100 sticks.

Yes, in my case both the Pluto and the Thunderbird were tested on the same configuration, same memory & timings, same operating system. So the Thunderbird was clearly slower clock for clock. I guess that, as others have pointed out, Thunderbirds were in fact slower, but were able to scale better and hit higher frequencies, so they were a "long term investment" on AMDs part. 😀
Intel also did the same (but on a MUCH bigger scale) with the Pentium 3 --> Pentium 4 jump. The first Pentium 4 CPUs were a joke, but they did catch up quickly, once the architecture evolved and they were also able to ramp up the clock speeds. Of course, nonetheless, the Netburst architecture remains a sad period in Intel's history.

Joseph_Joestar wrote on 2021-03-23, 09:47:

Yeah, the YMF7x4 cards are incredibly versatile. No other PCI sound card can provide the same feature set, without being paired with something else.

Yes, although I did have issues with them on Socket A KT600/KT880 systems (freezes in Quake 2 when changing resolutions or exiting the game). So on these PCs it's still better to go with a Creative Audigy 2 ZS/SB Live as a primary Windows card and keep the YMF724/744 card for DOS.

Joseph_Joestar wrote on 2021-03-23, 09:47:

On that note, I recently replaced my generic YMF724 with a Guillemot Maxi Sound Fortissimo which uses higher quality components and also has Digital Out (TOSLINK). It's amazing how much sound clarity one can get out of DOS games using that.

That card does look very nice, but it seems that it's missing a SBLink header, which is too bad (then again, it can be used on motherboards that don't have a SBLink connector anyway).

bloodem wrote on 2021-03-23, 11:35:

That card does look very nice, but it seems that it's missing a SBLink header, which is too bad (then again, it can be used on motherboards that don't have a SBLink connector anyway).

It has one, but it's not clearly labeled as such.

The JP6 in the bottom right corner is actually SB-Link. I've tested it on my Abit ZM6 and it works just fine. Kinda strange that they didn't label it properly as someone might think that it's a speaker/line out jumper instead.

Joseph_Joestar wrote on 2021-03-23, 12:04:

Kinda strange that they didn't label it properly as someone might think that it's a speaker/line out jumper instead.

Ha, that's exactly what I thought! 😁

Thanks to the wonderful people on this forum, we now have easy access to Athlon Golden Finger devices, so naturally I just had to revisit my Slot A build 😀

My Athlon "Pluto" Slot A 750 MHz was actually an 800 MHz part under the hood. Furthermore, it turns out that it's a golden sample - it overclocks LIKE CRAZY.
One of the first things I tried was to set the multiplier to 9, while also keeping the voltage at 1.6V. I was sure that the PC would refuse to POST, but not only did it POST, it perfectly booted Windows.
At first I thought that maybe the voltage was higher than I thought, or that the multiplier was not set correctly... but no. My motherboard has voltage monitoring and it was reporting 1.62V for the VCORE, and the frequency was in fact 900 MHz. Ran a bunch of benchmarks, no issues... however it did crash after 15 minutes of Prime 95 (small FFTs). Not a problem! Quickly increased the voltage to 1.65V and the system was rock solid after that. Amazing! Considering the fact that even original 900 MHz and 1 GHz Orion CPUs come with a default voltage of 1.8V, my CPU is definitely a top performer.

Of course, I also had to try 1 GHz and it did work, however the CPU needed 1.75V to be Prime95 stable. This is still below the default voltage for 1 GHz parts, but temperatures are a bit too high for my liking - apparently 45 degrees C idle/50 degrees C load as shown by the motherboard temp monitoring, but using a thermocouple on the back of the CPU, it turns out that actual temperatures are far higher: 63 degrees C. This means that the CPU die is even hotter, and let's not forget the cache chips which are most likely even more sensitive to heat.

So after a lot of testing, I finally settled for FSB110 x 8.5 multi @ 1.65V (935MHz). The speed is very similar to 1 GHz (FSB 100), but the CPU is a lot cooler. The cache runs at 2/5 divider which results in a whooping 374 MHz (higher than any Athlon in its original state).
Of course, I also added a lot of coolers (2 x 50 mm fans on the CPU, 1 x 120mm intake fan in front of the case, 1 x 120mm intake fan on the case side panel directly above the CPU, 1 x 120mm exhaust fan on the back of the case).

Some benchmarks with the 935 MHz overclock (they can be compared to the 750 MHz benchmarks in the first post, it's the same PC):

• With the GeForce 2 GTS card:

1Expendable 640 x 480 x 16 ---> AVG: 95.36 FPS / HIGH: 136 FPS / LOW: 67 FPS (no sound)
2
3GLQuake 640 x 480 x 16 ---> 362 FPS (with sound)
4
5Quake 2 640 x 480 x 16 ---> 227 FPS (with sound)
6
7Quake 3 640 x 480 x 16 --->  91 FPS (with sound)
8
93DMark 2000 ---> 6731 points
103DMark 99Max --> 7476 points (13787 CPU 3DMarks)

So, yeah... pretty similar to the P3 Coppermine 1 GHz - in some tests faster, in others slower (even though that one runs at 133 MHz FSB and it also has on-die full speed cache). Well, come to think of it, the Athlon has a dual pumped FSB, so it is higher 😀
This PC (the GA-7IXE motherboard in particular) is rock solid, did not have a single issue, everything just works - very similar to my 440BX builds, so I really like the AMD 751 chipset. Don't have experience with the VIA KX133 chipset, though; as I understand it should be faster, but not sure about stability.

Regarding the Super Bypass discussion: it was enabled. Turns out that on the later BIOS revisions of the Gigabyte GA-7IXE (version F7 in my case), Super Bypass is enabled by default when certain RAM timings are used (in my case it was enough to keep the timings on Auto, switching to lower manual timings actually resulted in decreased performance by 3 - 10%). More info about this can be seen on this German website: https://www.heise.de/ct/hotline/Speicher-Timi … rds-307644.html

Some pics taken during my tests:

I replaced the original CPU die thermal paste/cache thermal pads with Arctic MX-2 and Thermal Grizzly minus pad 8 thermal pads.
As can be seen in the first photo, the original cache thermal pads in particular were a joke, one of them was barely touching the cache chip (from what I read on Anandtech, this sloppiness was quite common at the time, especially for Athlons up to 900 MHz).

After doing so, temperatures at 1 GHz / 1.75V dropped significantly (55C during Prime95, as reported by my thermocouple).
Unfortunately, even though the CPU is Prime95 stable at 1 GHz, it's actually only 99% stable during normal use (there are a few random BSODs per day). Bumping the voltage even further does not help in any way.
So, my assumption is that it's related to the external cache chips. At 1 GHz (with the CPU's default cache divider: 2/5), the cache is running at 400 MHz, which is definitely pushing its limits. So I need to find a way to force a 1/3 cache divider on my motherboard.

Unfortunately I have yet to find a solution to the cache divider problem. I tried all possible software solutions (those created by H.Oda! 20+ years ago), tried to modify the Gigabyte 7IXE BIOS file with the FixCache utility, nothing worked... The divider is stuck at 2/5. Apparently there was another utility (WCPUA2B) created by H.Oda, and this one had been successfully tested with the F3 BIOS revision of the GA-7IXE. However, I was unable to find this utility anywhere 🙁
If anybody has any suggestions or a miracle workaround let me know 😀

UPDATE: I had to give up on software solutions for the cache divider problem (they are definitely a waste of time / not very reliable). Instead, I just swapped a few resistors on the Athlon PCB and, lo and behold, the CPU is now PERFECTLY stable @ 1 GHz with 1.75V.

You guys should come play with us!

Slot A: Aiming for the stars