I have the same board as you (iirc mine is rev E) here's a manual : http://www.elhvb.com/webhq/models/486vlb3/sis471g.html

The brand is Full Yes Tech (FYI). Mine also had fake cache, but real cache works fine on it. Have you populated the jumper headers ?

Also who made the bios you have ? Award or Ami ?

Deksor wrote on 2020-02-08, 08:28:

I have the same board as you (iirc mine is rev E) here's a manual : http://www.elhvb.com/webhq/models/486vlb3/sis471g.html

The brand is Full Yes Tech (FYI). Mine also had fake cache, but real cache works fine on it. Have you populated the jumper headers ?

Also who made the bios you have ? Award or Ami ?

Sorry i didn't put enough information.

It's Award BIOS. I never understood very well the cpu jumper settigns of this board. I usually used it with an IBM 5x86 but I knew that was "just working". I Used one of those utilities to check cache and failed. The jumper settings that boards came matched 256kb of cache.

I think I have exactly the same bios as you (I remember it was from summer 1994).

Can I have a picture of your board ? 😁

Here's:

I was dumping the bios chip so I removed it...

Thanks for the photo !
First thing I notice : the cache sockets are missing pins, I believe they've got all their pins underneath each chips, but just in case, are you 100% sure they make good contact ?

Also, the board doesn't officially support your IBM 5x86 (and it's lacking the 3.3V transistor, so if you don't have any adapter inbetween the CPU and the socket, you'll fry your CPU ! However you can easily install one if you want).
Have you tried the board and the cache with a supported CPU and fully configured, like a Intel 486DX2-66 ?

Have you tried to enable/disable the turbo mode ?

Yikes! I expected that those transistors places were "for another revisions". I never found reliable information about those, If you give me some models, I can put some equivalent/better transistors there.

The ol'turbo mode issue. At first, I used this board without the tubo switch with a 486SX-25 and was painfully slow. Then I put a blue lighting DX2-66 and barely improved. As last experiment, I put a switch in the turbo switch pins and PC improved a lot.

I soldered those sockets. The original fake cache was soldered. I checked it first and was fake (I broke the packages and were empty, also ran the board witout cache and still reports 256kb of cache). Those vias/holes never get clean properly, so instead of insist, I retired the socket pins, preventing to burn the board pcb. the unsupported CPU is a thing. In other boards, I put an unsupported CPU and cache never worked properly, but it caused data corruption. I turn it off and CPU ran slow, but ran. This is not the case: activated or not, post summary always report 256kb of cache, so cache is clearly hacked.

Yes indeed.
I've checked the bios of mine with some software I can't find anymore, and there was a setting with L2 cache to always report the size that's been configured. However when real cache installed, it should work. It does on mine and I haven't modified the BIOS.

Now for the transistor, that's true, you have to put one to get 3.3V. But you just need a LT1085CT in the large spot nearby the CPU socket.

It is documented here in the "CPU voltage" section : http://www.elhvb.com/webhq/models/486vlb3/sis486gd.txt.html
The reference I gave you is for Q6.
And here's a schematic where you can see where Q6 is supposed to be and in which order : http://www.elhvb.com/webhq/models/486vlb3/sis486gd.jpg

Ok, the regulator ( LT1085CT) you said is CRAZY expensive here (near 10 usd). Apparently is the only regulator that fits there. The other transistors are there for expand current capacity of the regulator, cooling it a little... But yes, is too goddamn expensive.

Well that's still cheaper than a 3.3v adapter that fit in the socket or a new motherboard that support 3.3 chips out of the box ^^

Clones of this transistor must exist though but I don't know them.

It's one of those quite propietary Linear Devices Products. Aren't bad at all. Good quality and well documented, but that isn't free. They are no standard LM/S/uP parts, so they not have clones. The other transistors are expensive too, but I have some bags of them, so there's no problem with those. If there's some recent bios version, It would be good. Bios barely fits in the 512kbit rom. I would check what about putting a 1M flash there, as the footrpint states, to add a IDE bios and CD boot rom (I think that PloP will suffice).

That sounds cool, how do you do that ? ^^