Repair, benchmarking and overclocking of a 486 mainboard: Soyo SY-030H 

Basically, anything above 3.7V is out of range of lx8383a because dropout 1.3V, MB's pdf says 4.0V for cyrix, it is possible only for low-dropout regulators with dropout 1.0V

Paying attention to classes at school pays off 😂. Simple and elegant explanation on the voltage regulation

Still have a soft spot for late 486 motherboards - while all of my friends at LAN parties could afford pentiums, a very similar motherboard served me well enough for years with a Cyrix 5x86-100 overclocked at 120MHz.

Good hint with memory stick during soldering, thank you! 🙏🏻

Seeing this old equipment calls to mind the time a colleague told me about working for a semiconductor manufacturer in the 70s. He ended up inheriting someone else’s logic diagnostic routine that would get stuck in an endless loop until a manual break command was issued. Anyway, the micro code (and silicon) was so primitive that it didn’t have an exception built into the code in case of a divide overflow, so of course every time the routine would run it would get stuck in an endless cycle trying to divide by zero, catastrophically overheat in the span of a few milliseconds, and destroy itself (and the ancient machine it was running in) spectacularly by blowing the lid right off the chip leaving a little charred cavity presumably where the ALU was. Took a while to fix that bug but he figured it out and everyone went on to live full and somewhat meaningful lives.

Thank you for telling and showing everything in such detail. It was interesting to see how the voltage regulator works in detail.

Hi, great video as usual. Just small note: that voltage regulator with higher current capability will be heated to same temperature as that other, because same amount of heat needs to be dissipated. 🙂👍

One generation after this, the Pentium 1, ignited my love for PCs, back when I was just a elementary school kid, so nice to see such old hardware being well cared and kept alive

Motherboards with soyo brings me back memories from my teens… That and a Cyrix processor 486 dlc

In essence, you've taken a "parts board" for someone else, and made it into a "working board" for you! It's amazing to take something where most people back in the day would just want to rip the guts out of this motherboard to fix a barely broken motherboard, and instead actually fix it!

For those who may be confused by why the resistor values did not fit: Some regulators have the 1.25 V reference voltage between output and ADJ pin, like the LX8383A, which follows the classic LM317 school. Other like the SHARP regulator (it seems to be a Japanese thing) went to 1.25 V between ground and ADJ pin, which also means they have an explicit ground connection at the IC. In any case trying to swap one for the other will result in the roles of R1 and R2 effectively being reversed, so the voltage output ends up wrong as observed. This is why swapping two resistors worked for the 3.45 V setting.

New video, I watch to enjoy What a first Saturday night to come, thanks for the upload

Ah, Soyo. Good memories. This was a preferred manufacturer when I had a pc parts vendor I worked with in the ‘90s.

Omg you are hardware genius, God. So much advanced stuff people don't know. It is pleasure to watch this old pc parts get restored and works improved. Just simply amazing

It's really true what a scholar once said, if you can't handle the fatigue of learning, you'll have to endure the pain of ignorance later. Like me, if I hadn't wasted time in school, maybe now I'd be making cool content like you.

8:16 all linear regulators emit the same exact amount of heat at a given input and output voltage! The output current rating is only the rating for load transient maximum current. Real current through the regulator is the current consumed by the load (use average value), and the dropped voltage is the voltage difference between input and output voltage. So if you have a 1A load, a 3.3V regulator running off 5V will always drop 1.7V and will always consume and convert to heat 1.7W of power. Higher current rating generally implies lower effective dropout voltage at high current, meaning the minimum necessary input voltage would be lower, but no advantage when you can't change the input voltage. There is one other thing, how well it removes heat. the 3A regulator has 3°C/W thermal resistance to tab, while your 7.5A one has 2.7°C/W. So it does run maybe a little cooler but not by much! You can afford to dissipate up to 10% more power on it before it hits the thermal limit, which means up to 5% more current, under ideal conditions. But to be kept in mind that the total thermal impedance also contains thermal impedance from tab to board, from board to air, etc, so in reality this small difference is even smaller yet, realistically it is zero. I don't suggest skipping the heatsink if you want to remain compatible with high current loads, and you should use high temperature rated inseparable thermal paste, not CPU paste. I keep HY410 for such use. But soldering the tab to PCB should also be pretty good. Putting a heatsink on top of plastic casing of a regulator is nearly pointless.

another one saved from the landfill! Thank you for sharing!

Very cool tests done with the motherboard. Congratulations on the video. Hugs from Brazil.

Oh man, thank you for the videos! I’m so burned out at work and this is the best refreshing for me 🙏

This was really satisfying to watch and a nice rebuild, a lot of effort put in but really well explained too - great detail! Makes me think I should resurrect some of my junk pile.

loved the long video and the repair, awesome job you did there, and calculations

Higher current specification of a regulator doesn't mean that it will be running colder. It has to dissipate the same amount of power regardless of its amp rating. Dissipated power depends on the voltage that the regulator has to drop and the current that it passes (P = V * I). That's why LDO regulators can supply quite more current (when supplied as low input voltage as possible) than non-LDO variants. And that's the same reason why switching regulators are used. For those input to output voltage difference doesn't really matter.

Fantastic tinkering and nice board, looking forward to more!

This was great, esp the part about the voltage divider! Thanks!

This is the first video of yours I've seen! I really enjoyed how you explained the changes you were making! It was very clear and enjoyable to follow along with 😃

A note about the regulator: A linear regulator is basically a variable resistor that turns all the excess voltage into heat. This means how hot a linear regulator gets is never related to how powerful it is, but rather directly to how much voltage it's dropping. if it's dropping 5V down to 3.45V, it will be dropping 1.55V, which means that at its limit of 7.5A, it will have to dissipate 11.6W of power, and at 3A any regulator is going to dissipate 4.65W of power regardless of their rated maximum (give or take a little bit depending on efficiency). This is different in switching regulators, which turn the input on and off for different periods (PWM) and then smooth out the output, meaning there's very little excess power at the cost of having a noisy output that needs very good filtering.

Love your work my friend keep it up!

I discovered recently that you can get SMD sample packs of the full E96 range of resistance values for relatively little money (£16). A set of 0603 and 0804 would cover most eventualities.

I could not make out if there was any USB on that board. I wasn't sure if you said 1985 or 95, I will watch again later on my TV, as I am busy at work. Another very informative video, thanks for sharing.

Nice to see it live again! 🎉

Man, you never fail to impress! Well done on this board.

As always good work. I have 2 soyo's to bring back to life. Apparently it would just be changing the swollen capacitors, but no. Socket 370, which was not booting, now heats up the processor and stops reading memory. The other socket 7 that sometimes booted and crashed, after I changed the capacitors the processor heats up and does not leave FFFF.

i like scrap computing approach with his vertical battery blaster for small battery spots like yours. The bios tweaking you showed is useful, thanks

Nice job you did. I like your content and look up to the next video. Greetings from Steven from the Netherlands

oh, WOW! I had exactly such a motherboard from SOYO! And I loved it for overclocking it with some AMD 5x86DX133 and clock of 50 MHz BUS (no, not 25 MHz, but real 50 MHz!) and multiplier of 3... This beast outruled every Pentium up to Pentium 90 including! 😀

You can use BAT85 diode for battery. It has lower voltage drop and it will hold bios settings for longer.

Just a tip: LDO's dissipate power only relative to their voltage regulation drop and current supplied to load. This means no rating on the LDO will change this and every LDO put in the board will be just as hot.

Very interresting content, especially about CPU voltage regulator. I like also informations about 486 dx/2 80MHz CPU. Most people use dx/2 66 or dx4/100 but dx/2 80 is forgotten. This CPU with 40MHz FSB in my oppinion is more interresting than dx4/100 with slow 33MHz FSB.

16:00 who cares if it looks a bit ugly? It does the job, it is soldered down properly and it allowed you to get on with the repair instead of spending more money and waiting for a few days for the parts. As a bonus, new parts don't need to be shipped to you which makes this repair even more environmentally friendly ;)

Actually if you look at the vast majority of DRAM specifications you'll find that they all pretty much settled on a refresh period of 15.6uS. This even carried over somewhat in to SDRAM. You have to go back a loooong way to find DRAMs that need to be refreshed much more frequently than that. But I think what you're seeing here is that DRAM refresh is already quite a small percentage of overall bus utilisation, and that a slower refresh rate is probably more of a power saving feature for battery powered devices than a performance enhancing feature.

I also have that BenQ lcd monitor :) Good to know: besides VGA It accepts 15khz rgb signals, so you can hook up Amiga and other retro platforms that use rgb scart connectors with an adaptor!

Awesome video as always!

So you know, Adrian would probably call a 33 minutes video, a "short" one. Great video nonetheless. Thank you.

Would be neat if fastdoom was added as a benchmark option. While original Doom is a good representation of how it would run back in the day, fastdoom would be a better representation for people who want to do some retro PC gaming on hardware and want to eke out a bit more performance on a less-ideal PC. Wonder if you could get Quake running acceptably (by the standards of the day of someone forced to play on a previous-gen PC :p) on that. I like the kinda chill almost liminal background music. :)

yeah Soyo always was a nice company back in the day.

Great work, thanks

You can run the Intel DX4 100 at a 2x multiplyer with the jumpers. I have a board set up with a 2x multiplyer and a 50Mhz fsb.

I have 2pcs of i486DX4/100 CPUs and the multiplier can be changed between 3x or 2x. And when these SiS497 can go up to 66MHz bus speed then 2x66 gives 133MHz. Both of those CPUs run at that speed with default voltage. Motherboard is Asus PVI-486SP3. PCI-bus don't like that post-write option anymore but when it's disabled, everything works.

Well done!

Hello! I am referring to your experience in board repair. There is a rare 624415-230 board with A80501-60 (Intel Pentium 60 MHz), the board is very similar to DFI THE LEOPARD, which is on The Retro Web site, the board starts, makes one peak, but there is no image with any video card, perhaps after one peak it freezes. There is a Dallas on the board, can it behave like this because of a dead battery in Dallas? The code on the postcard is 0088. If you remove the RAM, the board swears about it with a series of peaks in the speaker.

As usual great job ! I love watching your videos. And just out of curiosity I'll ask if you have in your collection the motherboard I once had in my first PC of my own ? It was a Zida/Tomato 4DVS.

I saw that you checked for unwanted battery charge current with the meter on the amp range, and apparently measured about 2mA. That's a lot for a lithium cell that is not intended to be charged. Maybe there's a meter problem...? You should ideally be using a milliamp or microamp range, and the charging current should be really a lot lower - even 10 microamps would be too much.

It should be possible with 486Dx4/100 to run @ 2x50MHz - I've had that setup with AMD 486 VT8.

Will 1MB of L2 cache work like 3D V-cache on AMD X3D CPUs and massively boost gaming performance? If you have a Voodoo 2 you can run Quake in this system and test 3D gaming performance 😁

To bad you did not put 128 MB Ram and 1 MB Cache on the board, that would be interesting. Anyway thanks for the video.

Wouldn't it be just easier to add a tp4056 or something similar to the battery mount meaning you can use a lithium battery without messing about with the board?

What is the name of the tool you use to straighten bent pins?

Enjoyable.

Shouoldnt it have been much faster though? It's benchmarking only barely faster than a DX2-66 even with a DX4 in there? Did I miss something?

12:40 -15:06 or short 2 jumpers - resistors paralel

Have you ever try to use supercapacitor in place of rechargeable battery?

Am I surprised an Intel DX4 wouldn't run at 120 MHz? Not in the slightest. Am I surprised an AMD DX4 labeled 100 _would_ run at 120 MHz? Not in the slightest. AMD used this as a secret weapon for _years,_ almost every builder knew that as long as your board could handle a 40 MHz bus, it didn't matter what speed your AMD 486 was marked. It was going to be happy with a 40 MHz FSB, maybe needing an extra 0.1V thrown at it. This was even true of their later 386/33 chips. They all happily ran at 40 as long as the board was good there. I also noticed some pins on IDE port 2 that are bent enough that they might be touching. That might be worth checking.

What about Overdrive CPUs on this board?

honestly, i never had much luck with the SIS 496/497. it was always kinda slow... my m919 w UMC chipset is much faster (with real cache ofc). but the funniest thing is that my m912 is by far my fastest 486 board, with a good vlb card (CHIPS vlb cards are absolute gold) i get 48-49 fps in doom with an amd 5x86 at 133. i just got an opti 895 board though, curious to see how that fares.

I'm curious how you disabled the charging circuit. Instead of moving the resistor, couldn't you just remove diode D2?

Did the resistors around the voltage regulator need to be adjusted because it's a different regulator to the original? Also, you put in a 3V CPU but measured 3.4V at the regulator and you were happy with that. Isn't the voltage too high?

Uhm I don't fully understand the mod you did to use a CR2032. Doesn't the power supply power the RTC by default when the system is on regardless of any mod? I modded several board but I only disable charging

I have even better variant or higher model then this MB but sadly it dead right now. I am troubleshoting it for years on and off and the last thing i will try is to change all tantalum caps.

Why were the resistors so out of spec originally?

Hello! Can you please share the image of your CF card?

I don't follow your math about the 1 MB of cache vs RAM size, so I must be missing something fundamental here... Isn't it more about the application you are running, and how much memory that app accesses, than the amount of physical RAM you have on the system? I mean, if your DOS app consume 1 MB of RAM, it will fit all in the cache and be super fast, but it has nothing to do whether you had 32 MB of RAM on the system or 512 MB. I'm confused... To me, cache has always been about optimizing the frequently used memory, however much memory you have behind that cache.

could you please share, what exactly you use as "deoxidiser" in your videos. Some magic spray witch I cannot find in google

I just got a Pc with an AMD DX2 66 and a QDI V4P895P3/SMT + Miro Crystal 10SD. I installed DOS 6.22 and it runs fine. I have my problems with DOS because I'm a little bit too young to know the syntax etc. Do you think it is a good idea to install Windows 95? Do I need to do anything to use the CD-Drive I've built in? The bios can't detect it. There is only the option to configure a master and a slave drive which works great for autodiscovering HDDs.

i think you should have used a different battery holder and not modify the power supply connector for safety and in the interest of keeping it as close to original within reason.

first!