feipoa wrote on 2022-06-06, 05:48:

Pardon my late arrival to this thread, but I couldn't help but wonder if anyone knows the rationale for disabling half the cache on the K6-2+ chips? With the Pentium Pro chips, I'm pretty sure that the difference between 256k, 512k, and 1024K was the presence of less cache, and consequently less manufacturing cost. For the K6 chips, was it just that the cost difference between 128k and 256k was less than the cost to have a dye with two cache sizes?

I think AMD targeted K6-3+ for embedded/industrial use because power hungry Athlons were no good there. They didn't sell any through retail. K6-2+ was a side product initially to get rid of those dies with actually malfunctioning half the cache, but as yields improved and there was not enough demand among industrial buyers for so many K6-3+, they had to sell these as K6-2+ anyway. It explains why 570MHz chips have so good unlock chance.

Just another successful mod, which I did on an overpriced AMD-K6-2+/570ACZ (570 MHz, 2.0 V originally). Paid way too much, 75 €, for the CPU thanks to the eBay's bad search system. It would have been great to have stumbled upon this thread before buying the CPU.
Relevant test system specs:
- Asus P5A-B Rev 1.04 (new polymer electrolytic capacitors, a.k.a. solid state capacitors), BIOS: 1011 Beta 005
- 384 MB PC-133 @ 100, CAS 3
- Windows 98 SE, with unofficial SP3-LITE 01-30-2019

Unfortunately, I did not do any before takes, so only the results are briefly mentioned here. After the mod, I have been running the CPU at 600 MHz (6x100 MHz) and 2.0 V, seems to be fine with that. Stability tested running Prime 95 Version 21.3.1 for couple of hours with K6 optimizations enabled. Also have run 3dmark 99 max and 3dmark 2000 several times after the mod, played briefly some games and done other random stuff. No crashes so far (after fixing some initial hickups mentioned later). See the cpu-z vintage and 3dmark99 max pro results in the attachment.

Couple of issues I encountered after I first did the mod:
- The system was unstable, any 3dmark run was guaranteed to fail. Also other crashes were happening, and even windows 98 start files got corrupted... Did not encounter these issues when running the CPU as basic K6-2+ before the mod.
+ This was fixed by fully recapping the motherboard with X-CON 6.3V 1000 uF, 7 mOhm ESR, polymer capacitors.

- There was RAM errors that were not encountered when the CPU was running as K6-2+.
+ For some reason, CAS setting had to be changed from 2 to 3 to get the RAM to work stable. RAM was running at 100 MHz frequency in both cases.

- On another note, not related to this mod; It seems the P5A-B is unstable in any configuration if PCI Delayed Transaction is enabled and there is a DMA capable ISA-card present. I think this might be quite a bummer, especially if using PCI-video cards. Now I am using Geforce 4 MX 440 on AGP and Voodoo 2 on PCI. Have not yet tested and compared how Voodoo 2 performance is affected with PCI Delayed Transaction disabled.

For mod testing, I just cleaned the cpu die, and the silicone at the corners of the IHS, and the corresponding spots on the ceramic casing. What remained of the silicone mold in the middle, nicely slotted the die with the heat spreader during testing so that it was in the correct spot. Just added a very small drop of Noctua's heat sink compound there. The CPU and the heat sink can also be seen in the attachment, during the phase when I had to remove the CPU while I was recapping the motherboard.

Would be interesting to have some values of the cpu power demand differences of these modded/overclocked K6-3+ compared to both the original K6-2+ setting and also the original clocked K6-2/3@250nm.

I tried to measure a difference with my at2atx adapter but they looked the same it was hard to tell though as the number flys all over the place. But it really seemed like no detectable difference. The chip may not actually shit down the extra, it may just map it out.

386SX wrote on 2022-09-24, 10:15:

Would be interesting to have some values of the cpu power demand differences of these modded/overclocked K6-3+ compared to both the original K6-2+ setting and also the original clocked K6-2/3@250nm.

The additional L2 cache doesn't seem to consume much. Actual power consumption varies significantly depending on FET quality and power supply topology, sync buck vs non-sync buck. I hope no one tries to use these with LDO.

Interesting. I imagine the cost of making only K6-3+ and disabling the cache on the less good ones was at that point a classic solution similar to those AM3 cpus with the unlock random results for the low end sector, considering final costs.

I peformed this mod today on a K62+ 533 I pulled from a broken Sony Laptop. I thought I had effed it up as the work on the resistor went a bit west but I managed to recover it and it posted... PHEW!. This chip clocks miles better than my original K63+ 450. I was messing about with that last night and it will only do 575mhz. I tried to set the FSB to 120mhz with the 450 but it wouldn't have it so I just left it like that. Popped the 533 in today after the mod and forgot the FSB was set to 120. It posted at 600mhz and went into windows. Not fully stress tested it yet but Did a sysbench and it went through a Quake Bench.

Will sit down with it this week and do some good testing with it.

So I reformatted the PC last night as the old Win98 install was a mess and I couldn't run 3DMark 99. 5x120mhz with all caches enabled seems to be the sweet spot with this CPU, although i've not fully stress tested yet I've had no crashed yet but that doesn't mean its 100% stable.

5x120mhz - 600mhz 2.2v
Iwill XA100 Plus 1.3 Aladdin V (Fully recapped with Panny Caps last week)
Crucial PC133 CAS 2 256mb module
3DFX Voodoo 3 3000 AGP @ 200mhz.

Looking back, On the same motherboard with my Genuine K63+ 450 at 550mhz with 128mb ram and the same Voodoo Card at 200mhz i managed to score the following

Bancho wrote on 2022-11-29, 12:29:

https://i.imgur.com/oGRC97Dh.jpg 5x120mhz - 600mhz 2.2v Iwill XA100 Plus 1.3 Aladdin V (Fully recapped with Panny Caps last week […]
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5x120mhz - 600mhz 2.2v
Iwill XA100 Plus 1.3 Aladdin V (Fully recapped with Panny Caps last week)
Crucial PC133 CAS 2 256mb module
3DFX Voodoo 3 3000 AGP @ 200mhz.

You managed to beat Celeron 300A@450 with Voodoo3 2000 and pre release driver 😉 https://assets.hardwarezone.com/2009/reviews/ … oo3/3dfx-v3.htm

How’s 3dm2000 look?

Hi all, today after some weeks that I had the idea to do it, I tried the mod.

I begin to be better on solder, and I make me courage to try to double the cache of my beautiful AMD K6-2+ 450mhz ACZ.

I found a lot difficult to remove the IHS, I passed about half an hour with my cutter to try to remove it. I don't know if I am unlucky but I found it completely hard and difficult.

Infact, after a lot of "war" I removed the IHS, but when I see what was remain under the IHS I had a bad view. Bad suprise.

This is one of my sadest days in experiment of my life. My loved processor is gone.

I never thought it was SO difficult to remove the IHS, if I knew I never tried this experiment.

I put now the photo. Bad day for me.

Sheesh man. Yeah. No offense but, You should have known from the pics how far to push in. Once you cut the four corners using a small razor use a large one to lift up one side until ‘pop’ and done. If you do it right it is pretty quick.

Someone wanna post a vid of it?

Sorry for the loss.

Check pm.

biessea wrote on 2022-12-11, 00:11:

Hi all, today after some weeks that I had the idea to do it, I tried the mod. […]
Show full quote

Hi all, today after some weeks that I had the idea to do it, I tried the mod.

I begin to be better on solder, and I make me courage to try to double the cache of my beautiful AMD K6-2+ 450mhz ACZ.

I found a lot difficult to remove the IHS, I passed about half an hour with my cutter to try to remove it. I don't know if I am unlucky but I found it completely hard and difficult.

Infact, after a lot of "war" I removed the IHS, but when I see what was remain under the IHS I had a bad view. Bad suprise.

This is one of my sadest days in experiment of my life. My loved processor is gone.

I never thought it was SO difficult to remove the IHS, if I knew I never tried this experiment.

I put now the photo. Bad day for me.

jeez what did you use an air fryer? a simple razor would have done the trick, sorry my man

Sorry man.

Repo Man11 wrote on 2022-12-11, 03:06:

Sorry man.

Thanks you all for the thought.

I am quite angry cause that IHS was terribly hard to take off. It was like minutes passed and no progress I made penetrating on the silicone under the IHS.

My patience was on an hard training then I made more strenght, and more, don't know when this damned IHS will go away from my processor.

And more the time passed, more I was becoming angry and without seeing a progress.

I applied more strenght, put it in a socket 7 motherboard to make it stay firm, but nothing better.

Fibally after 45 mins the IHS was gone, and this was the result. What a bad day.

Glad to hear (in pm) that you got a 400 1.6 V 3+ on the way those are usually pretty good chips. Feel free to give it up to 2.1v without a second thought btw. It’s just a normal k6-3+ binned for 1.6v 400mhz max living dangerously is prob 2.2-2.3ish 2.4 if you are a mad man

I've never had anything like this happen when decapping a K6-+ CPU. I wonder if years of use might harden the thermal material that AMD used, making it more likely to cause this? As far as I know, all of the ones I've decapped have had little to no use prior to my removing the IHS.

Repo Man11 wrote on 2022-12-11, 18:28:

I've never had anything like this happen when decapping a K6-+ CPU. I wonder if years of use might harden the thermal material that AMD used, making it more likely to cause this? As far as I know, all of the ones I've decapped have had little to no use prior to my removing the IHS.

Hey, I am not sure about thay, but probably years and years of working processors can make the material harder and more difficult to take off.

I passed truly about 45 mins of nightmare, I never be sure about of what I was doing, I never saw a progress about cutting edges, I become angry .

I tried a lot but the material was really hard and strong, I never thought about this, now I only can suggest to NOT DO IT.

I am sorryt but this is problably cause no one had uploaded a complete video about this threatment.

I will soon upload the video of this un-success, I am simply trying to make it.

Probably a lot of person will see that video and problably they will think more than me to do this modify.

IT IS NOT EASY LIKE OTHER WANT TO SEE IT IS.
If you have a precious AMD K6-2+ processor think a little bit before trying to do this mod, I am speaking sincere.

I am now THAT part of friend that says you "think about it, probably you don't really need it". And this is exactly what I think now, I didn't needed to, my K6-2+ to 450MHZ was running great for what I need to,

Have nice night you all.

Think about it.

Loris

It is easy, I imagine you got angry and went into frustrated rage mode 😀 To damage core you had to stab at least 2 cm deep under the spreader.

I can upload a vid of popping the ihs off. It is probably the easiest part of the mod. Everything else is pretty tough.

But you have to do it the way I show.

It has worked for me many times but that isn’t to say that it will work every time. I saw a user on another forum (beginning of this thread) who popped off a bunch of different k6 IHS and like all of them killed the die. Idk what they did, but this hasn’t been my experience on k6-+ chips. You are actually the first in the thread to kill their chip trying to take it apart. Don’t take this as a dis or attack. I’m not trying to do that. You obviously tried hard to avoid this. But let me show the way I do it, and maybe we can avoid it happening again 😀