Show us the pictures of chips with clear marking. The size of FPM RAM stick, unlike EDO, is determined by the smallest stick in the bank.

Let me see what I can do. The markings are really faint so I don't know how well they are going to show up on camera. I can't find a speed grade on them anywhere, it is possible I've got speed grades mixed as well which could be causing my problems because none of it is showing up now where before it was.

Here you go, these are the best close up shots I could get.

Well crud, now I'm getting HDD controller errors. As in, controller failed type errors. So I guess I could try and stuff a 16 bit HD controller in there instead of using the onboard one, or maybe try hanging a 3.5" drive off it (maybe the only reason it is failing is there is no HD attached). Or maybe it really is fubar due to something I did when I was trying to remove the corroded CMOS battery. I don't think I damaged anything but maybe I did.

So I got it to boot up last night, but only reliably with the original modules. The disk controller message may have had to do with the fact that I cut the CMOS battery off or that there was no HD connected. I put two of the new modules in again, and got the 16mb in one bank and 19mb in another. I had 2 4mb modules in the other bank, so this makes me think that the motherboard is incapable of handling 16mb 30 pin simms. Or maybe the RAM is bad. Not sure why it would report 16mb in the 1st bank when there is only 8, unless it is doing some odd.
I'm not sure. I wish I had a motherboard manual laying around so I could check it. Maulwurf1977, didn't you say you had a similar box? I'm sure you don't have the manual, but maybe you remember what the limitations for RAM were?

Where did you order the RAM? Those are parity modules (60ns), not really common on 486s outside of server and EISA boards. I had problems with a vendor with RAM failing in the 30MB area, I landed up swapping it out. The board in question certainly supported 16MB 30-pin SIMMs, so it definitely was defective RAM. There is no such thing as 8MB 30pin SIMMS, just 4MB and 16MB.

On 386 and 486 machines, 30pin SIMMs need to be installed in matched groups of 4, no exceptions. If the board is from 1993 or newer, it certainly supports 16MB modules. Boards from 1992 might be hit or miss, unless they are EISA based.

The seller is 1-800-4-Memory on Ebay. I haven't closed my dispute yet, I guess I'm going to have to see if they can send out another 4 modules. Even one set was 60ns and the other 70ns, wouldn't they all just run at the slower speed? Or must they all be the same speed? That may be harder to get, and I can't tell from the markings what the speed is. They were good about replacing the first set but I'm not sure they will send out another 4 modules. It is also possible that this board just doesn't support more than 16mb of RAM. I don't know for sure how old it is, I'd have to check the bios splash but that is no guarantee.

It took me two exchanges to finally get memory from them that actually worked right (they would flunk memory tests with flying colors if the machine was even able to detect it). I wouldn't be surprised if those SIMMs were the same defective units I returned!

Checked up the database, the pictures show 16M parity modules, 60ns, 16Mx1 structure.

As we're talking about 30-pin SIMM (I thought, you had more common 72-pin slots), you do have to insert 4 same sticks of RAM into each bank. Or are we talking about 486DLC? Pictures of CPU and motherboard would be helpful.

If you insert 2 16Mb stiks and 2 8Mb sticks in one single bank, you either get 32Mb RAM or nothing... It's the way it usually works for me.

Does your board have any onboard RAM soldered in? Switch it off if possible.

HDD controller failure in older systems occurs when there is no HDD or HDD is not powered/plugged. I'd say it was disabled in BIOS and you reset it to default by removing the battery.

There is no RAM on the motherboard. It has a 486dx2-66. There are 2 banks of 2 30 pin simm sockets.

So my friends over at 1-800-4-Memory are trying to tell me my motherboard may not be able to accept 16MB simms. What do you figure the odds are on that?
It has a full 256k of cache on it, so it seems like it would be able to hold a good bit of RAM. If it will only take 16 then that's all it takes, but it'd be nice to max it out.
Someone else upthread said there was no such thing as 8MB 30 pin simms, is that a sure thing? If not, seems like that might be the only way to get 32MB in this box.
16mb is still a nice pile of RAM for a 486, but the back 2 sockets will interfere with the sound card I found unless I can get low profile RAM (like around less than 1cm high).

Well crap. I just noticed something on the board, there is a tiny little area with silk-screening that reads:

Memtype: 256k, 1m, 4m
and then some jumper settings. So perhaps this board will only accept 4MB modules?

This is why it pays to go a little slow with some things and the silk screen is the give away that it is limited in module size. 4mb each still gives plenty for dos gaming but a lot less geek points.

Still, though, would be interesting to know why it detects 35MB and successfully posts. Sorta how some laptops are supposed to only work with 4gb dimms but will accept 8gb dimms. So I suspect it might actually support up to 32mb of RAM, but without 8mb simms I don't think there will be any way to accomplish that, if they all have to be matched.