I don't know wether that chipset is considered 'so cool'; it's just a very good S7 chipset. Stable, fast, many features. Sadly only official support for up to 66MHz fsb.
It's also not very exclusive at all. It wasn't a budget offering but there are lots of boards using it. It's a bit like the 440bx of Socket 7.

1. Can cache more than 64Mb of RAM.
2. Can be used in dual CPU setup.
3. First Intel chipset to fully adopt pipeline burst cache.
4. Integrated USB.
5. Good performance and overclocking.

That's about it. I think it's evenly matched by 430TX this days in various discussions though.

i430HX is arguably the best Intel So7 chipset, definitely for EDO:

- 512MB cacheable limit (with second Tag RAM)
- SMP support, so 2 CPUs possible
- faster EDO timings than i430FX or VX

For sure, HX is very good if there's dual tag designed into mother board. Most of these other HX based boards only come with soldered one tag SRAM, no else to add second. Micronics ATX boards does have solder spots for second tag but, there is no boards with dual tag soldered on so I could compare and install passive components or move SMD resistors (just like jumpers but soldered) to make second tag to work.

Cheers,

Yes, the 430HX has marginally faster EDO timing (4,7,10)-2-2-2 vs (7,9,12)-2-2-2 on the 430 FX. However, given by its server market orientation most HX motherboards came with 6 or 8 memory slots which require buffering and that kills any timing benefits over 430FX (EDO are effectively timed at FPM speeds). Some mainstream motherboards have workarounds to bypass buffers when less than 4 SIMM slots are used though.

After reading Oldie Tuning at Tom's Hardware the spring of 2001, I bought an Asus P55T2P4 for cheap on Ebay, and I ordered a K6-2+ 475 and a Pine PCI TNT2 32 megabyte video card from Tiger Direct. This was to replace a MB8500TVX with a Winchip 200 MHz CPU and a one megabite PCI card. It was a great upgrade, and rock solid with Windows 98.

For fun, I bought another in early 2008, and maxed out the RAM because a seller had 128 meg EDO SIMMs for cheap. Another system lost to the fire.

So, nothing special?

mpe wrote on 2020-08-29, 21:24:

Yes, the 430HX has marginally faster EDO timing (4,7,10)-2-2-2 vs (7,9,12)-2-2-2 on the 430 FX. However, given by its server market orientation most HX motherboards came with 6 or 8 memory slots which require buffering and that kills any timing benefits over 430FX (EDO are effectively timed at FPM speeds). Some mainstream motherboards have workarounds to bypass buffers when less than 4 SIMM slots are used though.

Most motherboards with >4 SIMMs? Hardly. By far the commonest i430HX board is the Asus P55T2P4 (mentioned above) with 4 SIMM slots. It was also used a lot in OEM desktop/workstation systems which invariably only had 4 SIMMs.

The combination of second tag socket and 4 SIMMs was uncommon, which made sense given 64MB would have cost more than the rest of the system back then - but the ubiquity of COAST slots in HX-days was a life saver here: any board with 256kB onboard cache plus tag *and* COAST slot to upgrade to 512kB could be upgraded with a module with another tag on it.

Hard to argue which motherboard config was the most common. But, if you have an appreciation for unique 430HX features (SMP, >64M cacheability, 512M RAM) then you'll be looking at boards with at least 6 slots and they'll be likely using buffered RAM.

Can you actually extend the tag using COAST slot? I thought 430HX boards with COAST and 256kB onboard still had second tag socket for >64M caching as you need more bits rather than size.

mpe wrote on 2020-08-30, 10:07:

Hard to argue which motherboard config was the most common. But, if you have an appreciation for unique 430HX features (SMP, >64M cacheability, 512M RAM) then you'll be looking at boards with at least 6 slots and they'll be likely using buffered RAM.

Can you actually extend the tag using COAST slot? I thought 430HX boards with COAST and 256kB onboard still had second tag socket for >64M caching as you need more bits rather than size.

You definitely need a second chip, so one on the board, one on COAST, or two on the board. I'm positive you could use the chip on the COAST next to the onboard chip on the revisions of P55T2P4 with COAST slot. Never tried it on different boards.

Agreed that SMP i430HX boards almost always have >4 SIMM slots, but uniprocessor boards were still very interesting as upgrade path (with K6Plus in particular) once >64MB RAM became realistic.

Here the computer...
https://drive.google.com/drive/folders/1-JzFO … HPxKBb0VRufzV2T

i think i only have the coast expansion slot and nothing on the mainboard

The bare mainboard to the right is a dual Pentium Pro, so probably an Intel 440FX chipset.

The Pentium mainboard has a Dimm-slot, so probably a 430VX. So max 64 MB cacheable. *edit* Funny, first Dimm I see on an HX. You'll need EDO on Dimm, no SDR-Sdram support.

do not consider the pentium pro, they are photographed close only because I wanted to sell them all together as the cards are interchangeable.

i think HX board can use EDO ram on both simm and simm168pin

Not sure whether you can use both simm and dimm EDO together. As both have to be 5V, it migh actually work, the Dimm is just one bank with one slot, as the simms need 2 slots per bank (I suppose).

Your cache is 256k, so max 64 MB buffered.

Does the system boot correctly?

AlessandroB wrote on 2020-08-30, 11:52:

Here the computer...
https://drive.google.com/drive/folders/1-JzFO … HPxKBb0VRufzV2T

i think i only have the coast expansion slot and nothing on the mainboard

Hardly the best showcase for i430HX. Don't judge a chipset on a lame OEM board. All this gives you vs i430FX is those tighter EDO timings. So no SMP, no higher cacheable limits etc.

I´m currently inspecting one of my 430HX mainbords. There are 2 x 256K of L2 cache and one 32kx8 TAG-RAM (in a 28pin socket) onboard.
In BIOS-setup there´s an option to enable 512MB cachable area, but the system won´t boot in this case.
There´s no second TAG-RAM socket present.
Did anyone manage to "upgrade" a second TAG-RAM or find any other way to provide the necessary 11bit Tag-bus to enable a cachable area of 512MB in cases like this?

Today I probed a little deeper into this issue.
Some mainboard manufacturers have obviously choosen the strategy of "crippling a feature" to save on costs here by providing one single socket for TAG-RAM on HX boards. To be precisely what they really spared was the costs of a second 28-pin DIL socket.
As long as there´s just one TAG-RAM socket present, the cachable area of the L2 cache is limited to 64MB of RAM. The single socket could even be populated witch a 32x8 chip (instead of the needed 16Kx8) without fixing this, because this SRAM design has 8 I/O lines only resulting in an 8-bit TAG-RAM bus-width.
For the Intel HX northbidge to enter the enlarged cache mode that allows all 512MB of RAM to be cached by L2 cache there need to be 3 additional I/O lines for a total bus-width of 11 bit.

This is done by adding a second TAG-RAM socket that is populated with a second 16x8 cache chip. Three of it´s I/O ports are used, 5 are left unused, ALL remaining pins like Vcc, Vss, address-lines, chip select, write enable and output enable are wired parallel to the existing (first) SRAM socket.
The 3 used I/Os need to be connected to the pins TIO8, TIO9 and TIO10 of the HX northbridge.

On first sight this looks like an easy job: Make a tiny daughterboard with one 28-pin plug at the downside and two 28-pin sockets on top, wire accordingly, populate with 2 x 16x8 15nS SRAMS and connect 3 wires for the additional I/O lines to the mainboard.
BIOS should take care of enabling a cachable area of 512MB at start with the correct register.
Maybe a pull-down resistor needs to be added at pin "TIO10" the turn the extended cacheability mode on.

Now here´s the situation on one of my HX boards:

The problem is, if the pcb´s layout does not provide a second TAG-RAM, the needed pins of the HX-northbridge (that sadly comes in the BGA324 package) might not be connected at all. In my case I detected a trace for TIO10 (probably just in case TIO10 needs to be pulled up) but could not find any connections to TIO9 and TIO8 so far.
It´s possible that there are just isolated pads for the soldering balls.
There are countless small traces and vias on the green pcb of the chip where there´s no plastic coating but I have no idea where they lead...
Maybe someone has an idea how to get a grip on the 3 pins / pads?

Meanwhile I managed to find a connection with pin TIO9. No luck with TIO8 so far. I think I´ll give ot a try anyway and prepare a small daughterbord for two cachechips while searching for TIO8.

The HX was a premium chipset on release but continued to be offered well into the TX lifespan because Intel gimped the TX to not compete with P6 offerings

By the time HX was no longer being used by boardmakers it was a low to mid range offering and super 7 was out.

I’ve had dimm only HX boards and boards with 6 simms

It’s amazing how useful a 6 simm board was,
Could pack 192mb of simms using relatively cheap 32mb simms, 96mb of cheap 16mb simms was another good option back in the day

This thread has me confused: I have this Chaintech 5IFM1 with 256k onboard cache, one TAG RAM soldered on, one currently empty TAG RAM socket and a slot for a COAST module.
If I use a COAST module with TAG RAM chip do I still need to install the chip in the currently empty socket?