"Spicy O'clock" project has started

[alxlab]

Yeah want it be better than tape.

Forgot to mention that when installing I would recommend slipping it on one edge first and then use a screw driver the bend the clip outward a bit on the opposite edge while pushing down . This will help prevent damage to lip on the clip that holds onto the edge of the 68040. Same procedure in reverse to remove the clip.

 

[yock1960]

Yeah want it be better than tape.

View attachment 4030

Forgot to mention that when installing I would recommend slipping it on one edge first and then use a screw driver the bend the clip outward a bit on the opposite edge while pushing down . This will help prevent damage to lip on the clip that holds onto the edge of the 68040. Same procedure in reverse to remove the clip.

This wouldn't work for me, as my humongous 128MB SIMM (physically and electronically) would interfere. I'm currently experimenting with my 2nd heatsink, which is physically a bit smaller, but has a central recess, that allows me to mount a fan. Currently it looks like it's keeping things a couple of degrees cooler. The fan is smaller than the recess...and rather noisy. I also wonder if rotating the heatsink 90 degrees might help a fraction, as there are open sides and closed ones and airflow might not be optimal in this orientation.

Time to make some measurements and go fan shopping!

 

[alxlab]

This wouldn't work for me, as my humongous 128MB SIMM (physically and electronically) would interfere. I'm currently experimenting with my 2nd heatsink, which is physically a bit smaller, but has a central recess, that allows me to mount a fan. Currently it looks like it's keeping things a couple of degrees cooler. The fan is smaller than the recess...and rather noisy. I also wonder if rotating the heatsink 90 degrees might help a fraction, as there are open sides and closed ones and airflow might not be optimal in this orientation.

Time to make some measurements and go fan shopping!

Got a picture of your Mac logic board? Curious to see what you're talking about.

 

[yock1960]

Got a picture of your Mac logic board? Curious to see what you're talking about.

I have a number of old heatsinks, collected over the decades. I no longer remember where this one came from and the original fan is long gone. It could almost have been made just for this application....if not for the humongous SIMM. I tried rotating it, so the airflow would have an easier path to the system fan, but didn't like the fit. Speaking of fit, there can't be much room, if any, above, when the case is on! With my current overclock of 36.89mhz, I'm seeing just under 37C after running MacBench, about 2C less than my previous arrangement. I have a 40mm Noctua on order, will it make a difference??

 

[JDW]

I have a 40mm Noctua on order, will it make a difference??

In terms of noise, yes it will be an improvement over most 40mmx10mm fans. In terms of airflow and cooling, maybe not. Noctua keeps noise in check by selling fans with only modest RPM speeds. If you have a very noising 40mm fan in there now, I'll take a guess the RPM speed is higher than that of the Noctua and therefore moves a bit more air. But you would need to compare specifications of both fans to know a little bit better. Even so, I've seen some really weird specs printed on fan labels before, so the best test is to plug them in and put your hand in front to gauge the airflow.

 

[yock1960]

Here is another option I have, I even was able to slip a thermocouple underneath the fan! Fits perfectly and plenty of clearance (definitely no clearance on the other). Much less mass in it though, so I wonder, I guess I would just have to check it. BTW, these are apparently still available! God only knows how long this has been lurking in my parts bin.

 

[alxlab]

Ah an LC 475. Yeah those are tight. The 8MB stick is even taller than your stick and overlaps the CPU quite a bit.

I actually found a couple for auctions for the low profile 45mm with fan heatsink you got. It seems to be originally for geforce 256 cards. It also seems to have 2 models:

MOTHR-1024-C

MFAN-1024-D

https://www.ebay.com/itm/254247563521?hash=item3b3255f101:g:UGMAAOSwYhtc7qWe
https://www.ebay.com/itm/134037172218?hash=item1f353ceffa:g:H3wAAOSweK9h2qho

Who knows what their availability will be like in the future, but I'll try to get one so I can make a clip for you.

 

[JDW]

View attachment 4071

https://www.ebay.com/itm/254247563521?hash=item3b3255f101:g:UGMAAOSwYhtc7qWe
https://www.ebay.com/itm/134037172218?hash=item1f353ceffa:g:H3wAAOSweK9h2qho

Who knows what their availability will be like in the future, but I'll try to get one so I can make a clip for you.

That heatsink with embedded fan looks pretty slick, and it certainly is the lowest profile fan you can find, but with few fins compared to the 45x45x10mm gold-tone heatsink that I currently use, I wonder if the embedded fan version heatsink really offers the same amount of cooling. Fan noise may also be more of an issue as compared with Noctua, although that is just speculation on my part since I've not tried one of those.

What would really be ideal is a 100% copper version of the 45x45x10mm fan that I use, but so far, all the heatsinks I've seen are aluminum. Aluminum isn't bad at all. Copper is just better.

Naturally, I'm thinking only about the LC575 motherboard and not the LC475. SIMM location would appear to create issues with the size of a heatsink and fan on the 475.

 

[alxlab]

Also found this that seems to be similar but with clips on the side. Found them on Aliexpress with search heatsink 4041s:

https://www.aliexpress.com/item/32542931108.html

 

[alxlab]

That heatsink with embedded fan looks pretty slick, and it certainly is the lowest profile fan you can find, but with few fins compared to the 45x45x10mm gold-tone heatsink that I currently use, I wonder if the embedded fan version heatsink really offers the same amount of cooling. Fan noise may also be more of an issue as compared with Noctua, although that is just speculation on my part since I've not tried one of those.

What would really be ideal is a 100% copper version of the 45x45x10mm fan that I use, but so far, all the heatsinks I've seen are aluminum. Aluminum isn't bad at all. Copper is just better.

Naturally, I'm thinking only about the LC575 motherboard and not the LC475. SIMM location would appear to create issues with the size of a heatsink and fan on the 475.

Yeah heatsink and fan size can really vary depending what model computer you planning to use. Think I can fit a really tall heatsink and fan in an LC 630 no problem, but less so in a Color Classic and even less in the LC 475.

I did find some copper heatsinks that might work for you JDW. Ideally I would want as close to 47.2mm (size of the 68040) but all I've found is either 40mm x 40mm x 10mm or 50mm x 50mm x 15mm.

The 50mm one seems to be out of the question for you due to height but the 40mm should work. I guess it would be better than the 45mm aluminum heatsink due to increase thermal conductivity and a lot more fins (20 vs the 12 of the aluminum).

https://www.aliexpress.com/item/4000107291369.html

It's of course a lot more expensive than the aluminum heatsinks but $15 CAD shipped isn't too bad either.

 

[yock1960]

Ah an LC 475. Yeah those are tight. The 8MB stick is even taller than your stick and overlaps the CPU quite a bit.

View attachment 4068

I actually found a couple for auctions for the low profile 45mm with fan heatsink you got. It seems to be originally for geforce 256 cards. It also seems to have 2 models:

MOTHR-1024-C

View attachment 4069

MFAN-1024-D

View attachment 4071

https://www.ebay.com/itm/254247563521?hash=item3b3255f101:g:UGMAAOSwYhtc7qWe
https://www.ebay.com/itm/134037172218?hash=item1f353ceffa:g:H3wAAOSweK9h2qho

Who knows what their availability will be like in the future, but I'll try to get one so I can make a clip for you.

I ended up not testing it, although the only way to find out anything, would be to test it. After some research, I get the feeling that the low surface area will reduce it's effectiveness. I do know that the other heatsink/fan is starved for air with the case on. After the Noctua fan comes, I'm going to try to do a better job of getting the fan completely seated on the sink, perhaps creating just a smidge more of clearance. Another idea is to gang some smaller, shorter sinks, to attach a fan to. I already have them, they are about half the height of the one in your pic. Again, would require experimentation. The ultimate, ghetto solution would be to leave the bigger sink I originally had on, hack a hole in the case and mount a fan overtop.

 

[JDW]

Yeah heatsink and fan size can really vary depending what model computer you planning to use. Think I can fit a really tall heatsink and fan in an LC 630 no problem, but less so in a Color Classic and even less in the LC 475.

I did find some copper heatsinks that might work for you JDW. Ideally I would want as close to 47.2mm (size of the 68040) but all I've found is either 40mm x 40mm x 10mm or 50mm x 50mm x 15mm.

The 50mm one seems to be out of the question for you due to height but the 40mm should work. I guess it would be better than the 45mm aluminum heatsink due to increase thermal conductivity and a lot more fins (20 vs the 12 of the aluminum).

View attachment 4075 View attachment 4076
https://www.aliexpress.com/item/4000107291369.html

It's of course a lot more expensive than the aluminum heatsinks but $15 CAD shipped isn't too bad either.

For most people, the gold-toned 45x45x10mm aluminum heatsink shown in my Spicy Part II video is probably just fine. Using only 2 screws, a 40mm fan mounts well on top. You also made a wonderful 3D printable clip for it, such that decent thermal paste can be used. I'm definitely going to give your clip at try at some point!

 

[alxlab]

I ended up not testing it, although the only way to find out anything, would be to test it. After some research, I get the feeling that the low surface area will reduce it's effectiveness. I do know that the other heatsink/fan is starved for air with the case on. After the Noctua fan comes, I'm going to try to do a better job of getting the fan completely seated on the sink, perhaps creating just a smidge more of clearance. Another idea is to gang some smaller, shorter sinks, to attach a fan to. I already have them, they are about half the height of the one in your pic. Again, would require experimentation. The ultimate, ghetto solution would be to leave the bigger sink I originally had on, hack a hole in the case and mount a fan overtop.

Yeah putting a hole in the case is one way to fix the height issue. I messure the clearance on mine and realistically you could fix a heatsink and fan is the total height is 15mm or less.

This a good example where a heatsink would be ideal if it put the heatsink directly above the case fan.

I guess another option would be to use a blower type blowing on the side of the heatsink if you don't mind more noise and figure a way to mount.

Both the heatpipe and blower options seem like interesting project all by themselves.

 

[yock1960]

I know that JDW talks about this in his videos, but does anyone have any idea as to why booting from floppy is so much more reliable?

Is the SCSI chip just less resilient to overclocking? Or possibly this relates to modern SCSI replacements, since I'm using SCSI2SD. Once booted however, there seems to be no issue or nearly none. I do seem to recall one freeze after boot...IIRC, the system was just idle, but frozen...only once though.

Since performing a recap (my 1st), hanging at boot has become much more common. I did have an 'apparent' issue that turned out to just be related to SCSI ID; once I made my boot drive 0 instead of 4, the issue went away.

This morning, I had the idea of doing some floppy disk booting. No hangs. Increased the overclock on every restart, no hangs. Even forgot to insert the floppy once...my highest ever overclock of 40.45mhz and it didn't hang!

I know we are using these machines 'out of spec', but the apparent randomness of the issue is confounding!

What are others of you experiencing? This could be a quirk of my machine, or of LC475's in general. There's also that I'm still using the MC88920, but I assumed that recapping would make things more consistent, not less! Also, who knows the actual pedigree of my Ebay MC68040! Once I'm successful with the replacement of the MC88920, things may become clearer...and more predictable!

 

[yock1960]

Aha! Now I understand. It doesn't matter what you set Spicy O'clock to, above a certain point, your clock generator has a limit and won't go higher! I didn't get this before...translation software has some way to go yet!

Well, I've found my limit with the MC88920, which is ~40.5mhz. So, now I wait for the MC88196DW80.

At least, with hints from JDW's videos, I stumbled upon a dependable boot procedure; Boot from floppy, restart from SCSI. This procedure is still faster than was starting my computer at work, with it having to negotiate with servers/security protocols!

There are two SCSI2SD settings I should try and see what effect they have on booting:

1) FAST/SLOW currently set to FAST

2) SCSI1/SCSI2 currently set to SCSI2

 

[yock1960]

Well shucks, there doesn't seem to be any faster VRAM available, now that I can finally make use of it!

 

[yock1960]

Well, I never would have believed that I could reach the lofty heights that I have reached in overclocking my LC475 when I started down this path, just one month ago! So much has happened in that time, that it seems more like 3 months have passed.

Many thanks to @Kay K.M.Mods for making Spicy O'clock, @JDW for the huge effort of making the videos and a whole host of other folks on Youtube who share techniques on working on this type of hardware and make it look easy enough for a klutz like me to try! Oh, and also @Mr. Fahrenheit who supplied me with his 60ns VRAM, which arrived today and has enabled me to reach 49.02mhz. I will try to exceed this tomorrow, but even if I can't....I'm still ecstatic!

 

[Kay K.M.Mods]

Well, I never would have believed that I could reach the lofty heights that I have reached in overclocking my LC475 when I started down this path, just one month ago! So much has happened in that time, that it seems more like 3 months have passed.

Many thanks to @Kay K.M.Mods for making Spicy O'clock, @JDW for the huge effort of making the videos and a whole host of other folks on Youtube who share techniques on working on this type of hardware and make it look easy enough for a klutz like me to try! Oh, and also @Mr. Fahrenheit who supplied me with his 60ns VRAM, which arrived today and has enabled me to reach 49.02mhz. I will try to exceed this tomorrow, but even if I can't....I'm still ecstatic!
View attachment 4590
View attachment 4589

Well done yock1960 !

 

[JDW]

Interesting to see tantalum caps on the motherboard, which seems to indicate power stability is less of an issue on that board than it is on the LC575 board. On the LC575 motherboard, both @Kay K.M.Mods and @Drake informed me that that couldn't overclock very high until they recapped (and in Kay's case, removed the tantalum caps) with OS-CON super low ESR capacitors. In my own case, I used OS-CON too, but I never used tantalum on it. I merely swapped the stock caps with OS-CON.

ESR of those tantalum caps is close to 700mΩ, whereas OS-CON is close to about 25mΩ.

In any case, congratulations!

 

[Kay K.M.Mods]

Interesting to see tantalum caps on the motherboard, which seems to indicate power stability is less of an issue on that board than it is on the LC575 board. On the LC575 motherboard, both @Kay K.M.Mods and @Drake informed me that that couldn't overclock very high until they recapped (and in Kay's case, removed the tantalum caps) with OS-CON super low ESR capacitors. In my own case, I used OS-CON too, but I never used tantalum on it. I merely swapped the stock caps with OS-CON.

ESR of those tantalum caps is close to 700mΩ, whereas OS-CON is close to about 25mΩ.

In any case, congratulations!

Oh I overlooked it! I couldn't exceed 43Mhz when I was using the Tantalium on the LC475 like yock1960. BTW, I have recorded a maximum of 51Mhz with the OS-CON now. @JDW was referring to power supply stability, but I think there are other reasons as well...