Some Pentium systems can be de-clocked using a specific key combination (usually to AT speed) while running a real mode OS. It is possible that this also applied to the Gateway systems with this particular case, and then the Turbo light would have come on when the system was de-clocked (meaning it was actually a "De-Turbo"-light 🤣 ).

Some Pentium boards, especially earlier 430FX ones, have actually functional Turbo switch headers that disable external and/or internal cache to bring the system down to 386/486 levels. Some later Pentium boards have functional Turbo switch headers that set the FSB down to 50MHz. It is useful in either case.

There is also that the case is probably not made for Pentiums, but for a broad range of PCs from a specific OEM vendor, and might have been used for 486 systems, as 486 and Pentium co-existed through the second half of the nineties.

That case was used with 486 towers with just a different sticker.

I actually have two Socket 7 boards with working Turbo:

1) Lucky Star LS-P54CE. It's a 430VX baby AT board with turbo pins. Going turbo changes FSB speed from 66 to 50 MHz.
2) Intel's Advanced/ML board. It's a 430HX ATX board. Going turbo means getting roughly 386 speeds with a Pentium 166, but I don't remember exactly. I think it's done by disabling L2 cache. Since it's an ATX board, there are no pins for turbo switch/LED, so everything is being done via keyboard shortcuts. I think this feature is present in every Intel's Socket 7 board (and even Socket 8, but disabling L2 cache really decimates Pentium Pro performance).

Reminded of the stories of users accidentally toggling the Turbo mode and then complaining that their computers are 'slow'. Customer support must have got a lot of calls like that in those days.

jheronimus wrote:

I actually have two Socket 7 boards with working Turbo:

1) Lucky Star LS-P54CE. It's a 430VX baby AT board with turbo pins. Going turbo changes FSB speed from 66 to 50 MHz.
2) Intel's Advanced/ML board. It's a 430HX ATX board. Going turbo means getting roughly 386 speeds with a Pentium 166, but I don't remember exactly. I think it's done by disabling L2 cache. Since it's an ATX board, there are no pins for turbo switch/LED, so everything is being done via keyboard shortcuts. I think this feature is present in every Intel's Socket 7 board (and even Socket 8, but disabling L2 cache really decimates Pentium Pro performance).

Is it Boot Speed Turbo/Deturbo under the boot setting on the BIOS? or is it System Cache under the boot setting?

I used to own a Gateway 2000 system from that era that didn't have a physical turbo button, but did have a "CPU Speed" option in CMOS setup that could be set to either "Fast" or "Slow," accomplishing the same effect. So it should be possible to toggle the "Turbo" mode on these machines, even though it's cumbersome to do so.

I have that same case, but instead of "P5-90" it says "4DX2-66". So yeah, same case repurposed. Although IIRC mine does have a Turbo button.... which begs the question, if you're modifying the mold anyway... why not drop the Turbo LED too? Hmm. Curious.

It's a great case though. So many drive bays! My one complaint is that the rear hard drive cage has to come out to service the PSU. 🙁

I have a Gateway P5-60 Desktop myself, very similar to the Tower you show. You can trigger the "Turbo" LED with CTRL and + or - . So it works just with a turbo button on the case, only that it uses a key combination instead.

I wish I could nab one of these towers one day.

jheronimus wrote:

I actually have two Socket 7 boards with working Turbo:

1) Lucky Star LS-P54CE. It's a 430VX baby AT board with turbo pins. Going turbo changes FSB speed from 66 to 50 MHz.
2) Intel's Advanced/ML board. It's a 430HX ATX board. Going turbo means getting roughly 386 speeds with a Pentium 166, but I don't remember exactly. I think it's done by disabling L2 cache. Since it's an ATX board, there are no pins for turbo switch/LED, so everything is being done via keyboard shortcuts. I think this feature is present in every Intel's Socket 7 board (and even Socket 8, but disabling L2 cache really decimates Pentium Pro performance).

My TC430HX has turbo too. It's CTRL-ALT-(+) for turbo, and CTRL-ALT-(-) for deturbo, i hear a low pitched beep for deturbo and a high pitched beep for turbo. and i remember that none of the Phoenix BIOS based Socket 7 Intel boards (AN430TX and LT430TX) don't have that turbo function.

As mentioned, the turbo light did report the turbo status, which could be set to "deturbo." Gateway used Intel motherboards, and the P5-75/90/100s used the Plato+Neptune board which could be set to "deturbo" in BIOS or by CTRL-ALT-"-" (as long as the machine was not in protected mode. You cannot use this key combo after loading, for instance, EMM386).

In either case, the "deturbo" mode didn't actually target a specific speed, it just disabled the cache and supposedly introduces some dummy cycles to the CPU. Deturbo on my Gateway P5-90 brings it down to the level of a high-end 386 which is good for a lot of games of the Wing Commander era and is more graceful about it than some of the software throttlers.