NitroX infinity wrote:

A few questions regarding super socket 7 and it's processors. […]
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A few questions regarding super socket 7 and it's processors.

1) Socket 5 cpu's fit in a Super Socket 7 socket?
2) S5 & SS7 multipliers are freely adjustable downwards? What about upwards?
3) Is there a performance difference between the P54C and P54CS Pentiums at equal speeds?
4) Do I need to put thermal grease between the cpu and heatsink?

I'm asking these questions because there is some doubt and some 'not known' about it for me.

1. Yes
2. Yes, but a AMD K6-2/3 2x multiplier is 6x internally. Some late MMX CPU have 1.5x remapped to 3.5x internally. Original non-MMX Intel Pentium maximum 3 multiplier, the MMX goes to 3.5
3. Unknown, but I serious doubt any noticeable difference.
4. No

So it's possible to set a P54C to a multiplier of 1 to have a 66MHz CPU?

NitroX infinity wrote:

So it's possible to set a P54C to a multiplier of 1 to have a 66MHz CPU?

No, 1.5x is the lowest. With the lowest FSB setting of 50mhz you get 75mhz, though it is rumored that some early Socket5 boards allowed for 40mhz FSB .

Remember chipset plays a BIG difference on the Pentiums. See my benchmark results here:
Pipeline burst cache performance boost on Socket 7 - benchmark results

NitroX infinity wrote:

A few questions regarding super socket 7 and it's processors. […]
Show full quote

A few questions regarding super socket 7 and it's processors.

1) Socket 5 cpu's fit in a Super Socket 7 socket?
2) S5 & SS7 multipliers are freely adjustable downwards? What about upwards?
3) Is there a performance difference between the P54C and P54CS Pentiums at equal speeds?
4) Do I need to put thermal grease between the cpu and heatsink?

I'm asking these questions because there is some doubt and some 'not known' about it for me.

1) Usually they do, but it depends on the voltages the motherboard can provide (though I know of no Socket 7 motherboard that isn't capable of supporting single rail CPU's)
2)You can adjust the multipliers on the motherboard. The question is, will the selected multipliers work with the CPU you intent to use. I know some MMX Pentiums have some of their upper multipliers disabled (I tested this myself)
3)Not that I know of
4)That depends on what heatsink you intent to use. If you use a tiny passive Socket 7 heatsink without a fan on say an early Cyrix or early K6, then even thermal greace won't help you.

@Vetz: I'll be using an AOpen AX59-Pro with Via MVP3 chipset on which I'll be using AMD, Intel and hopefully Cyrix and other cpu's.

NitroX infinity wrote:

@Vetz: I'll be using an AOpen AX59-Pro with Via MVP3 chipset on which I'll be using AMD, Intel and hopefully Cyrix and other cpu's.

Is this for your benchmark project?

If that is the case, you could consider doing it on more "period" correct board with the 430VX or HX chipset released in 1996. Just my consideration 😉

Again, depends if you intend to max out on 233 MMX or if you're going full out on AMD K6-III on the same board.

All the way up to K6-III+ and K6-III @ 600MHz.

NitroX infinity wrote:

All the way up to K6-III+ and K6-III @ 600MHz.

SS7 is the way to go then 😀

Though I've noticed that my Aopen AX59-Pro board won't let me overclock my K6-III+ to 600. It boots, but restarts and give all sorts of erros. It is stable on my Epox MVP3 board, so it is really strange.

Hmm, something to keep in mind then.

NitroX infinity wrote:

Hmm, something to keep in mind then.

Another thing you might want to keep in mind is the hight difference between different CPU's. While a CPU cooler might fit a flatter CPU (like the plastic MMX's) perfectly, the higher ones like the Cyrix's might be a tight fit. I once broke a tab while trying to install a CPU cooler on a Cyrix.
Keep in mind to not apply too much force, it's best to either bend the clip a little on a spare cooler or to use a different cooler altogether 😉

About the multipliers: As the others already said, the board just gives the CPU three signals (BF0, BF1 and for later CPUs BF2) and the CPU selects a multiplier from this.
The K2-2/3 also interprets 1.5 as 3.5 just like the Pentium MMX. (Of course nobody wanted to run such a CPU with an actual 1.5 multiplier.)
On the K6-2+/3+ the multiplier is also settable by software, a 2x multiplier is accessible that way.

The AMD K5 is even crazier. From http://www.pcguide.com/ref/cpu/fam/g5K5-c.html:

1Motherboard Multiplier Setting   CPU Interpreted Multiplier   Processors
21.5x                             1.5x                         K5-PR75 (75 MHz), K5-PR90 (90 MHz), K5-PR100 (100 MHz)
32.0x                             1.5x                         K5-PR120 (90 MHz), K5-PR133 (100 MHz)
42.5x                             1.75x                        K5-PR166 (116 MHz)
53.0x                             2.0x                         K5-PR200 (133 MHz, not released)

(The K5-PR166 is rare, though.)

To hit 600 MHz on the K6-III+ it will need more volts. The chip I have is rated at 1.6V and for 600 MHz it needed 2.something. It was just for benchmarking though.

Everything else has been said already, nothing to add 😀

idspispopd wrote:

On the K6-2+/3+ the multiplier is also settable by software, a 2x multiplier is accessible that way.

It is also accessible by jumpering 2.5x, which is remapped to 2x on K6-2+/3+. 😉

NitroX infinity wrote:

4) Do I need to put thermal grease between the cpu and heatsink?

I see no reason not to use thermal paste,it will just keep the cpu cooler,which is never a bad thing.

I don't, but this is more because I keep changing the CPU all the time 🤣

These Socket 7 chips don't produce that much heat. 20W maybe?

Mau1wurf1977 wrote:

To hit 600 MHz on the K6-III+ it will need more volts. The chip I have is rated at 1.6V and for 600 MHz it needed 2.something. It was just for benchmarking though.

Everything else has been said already, nothing to add 😀

You are correct that it will require more volt, but even 2.6V with heavy cooling won't let the Aopen board run at 600mhz. The Epox board only requires 2.1V with the same CPU.

Interesting. I did the 600 MHz run on the DFI board. I believe I set it to 2.3V or something like that.

Running a K6-2+/3+ at 600MHz is not just a matter of raising voltage. Most of it has to do with luck. I have a K6-3+ 400 ATZ which I've been running at 550MHz (1.9V) since day one. It runs perfectly fine, but no matter what I do, I can never get it to boot at 600MHz. I have managed to make it POST with 2.4V or something, but it always hangs somewhere along the way. FYI all of this was tried on a ALi Aladdin V board, the GA-5AX rev 4.1.
50MHz on this chip is so trivial anyway. If you're obsessed with it, you could try raising the FSB beyond 100MHz and lowering the multiplier until you hit a sweet spot like 575MHz.

A K6-3+ at 550MHz is about as fast as a Pentium 2 400. Most of the times it is a little bit slower, sometimes it can be a little bit faster.

pushing a k6-2+/k6-3+ to 600mhz is not really encouraged.

first, some individuals may run stable at that speed without additional voltage, but it does involve some luck.

second, according to amd's datasheet, the absolute vcc limit(that can cause damage) is only 2.2v for 0.18um k6s, and 2.6v for 0.25um k6s, so its rather risky especially for a k6-3+ thats pretty hard to find.

third, many have found that for socket7 boards, 6x clock has inferior memory performance to 5.5x, which negatives the improvement from the additional 50mhz. according to my tests, actual performance of 600 is only about 2% faster than 550 on a 5ax, in contrast to a 9% clock increase.

you can try 105*5.5 instead if you really want to go faster, which is 5% faster than 550.