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Soyo 5TA2 Socket 7 motherboard advice

Z

Zippy Zapp

Experienced Member
Joined
Dec 13, 2014
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259
Location
USA:CA
Hi,

I found this motherboard at a local thrift store for $3. I have no idea if it works yet because I haven't had a chance to throw some RAM in it and a video card and hook it up. It seems to have a Pentium 90 CPU installed with no heatsink which makes me a little leery about heat. I have a cooler with sink and fan I can put on it. I also have an AT Power supply to test it with and a ISA VGA card. I don't think I have any PCI VGA cards.

It seems to be a model 5TA2 and I found this link that seems to match:

http://stason.org/TULARC/pc/motherboards/S/SOYO-COMPUTER-CO-LTD-Pentium-SY-5TA2-SY-5TA5.html

My questions boil dow tow:

1. Compatible RAM
2. Cache RAM and Sockets
3. VRM Socket
3. Available PDF of the manual

1. I wanted to make sure I had the correct SIMMs before I installed them. I have 32MB 8x32 EDO which should work but the specs on the link above show 8x36 which I am pretty sure is parity. I would be surprised if this was required.

2. Cache appears to be 256k. They don't use all the pins in the socket and I seem to recall this was ok because other Cache SRAMs were probably compatible that had more pins.

3. What is the VRM socket used for? I don't recall seeing this on the other 286 - 486 systems I built.

4. Does anyone have any available PDF or manual scans of this model?

Any insights or help would be appreciated.
 

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Thanks but I already posted that link in the original post. :p Manual would be great but seeing how they went out of business a while back it might not be likely. I never owned any Soyo and IIRC they were somewhat on the low end.

One other thing pops up to: the RTC. I don't see a place to plug in an external battery so that will have to get replaced.
 
That sure seems right. Thanks for posting it I will compare it to the board when I get home today. Nice find!
 
Zippy Zapp said:
1. I wanted to make sure I had the correct SIMMs before I installed them. I have 32MB 8x32 EDO which should work but the specs on the link above show 8x36 which I am pretty sure is parity. I would be surprised if this was required.
Click to expand...

By the time of the Socket 5, most boards accepted either FPM or EDO memory types. As for parity, it depends on chipset support. Some boards that didn't support parity could use parity modules and some couldn't.

Zippy Zapp said:
2. Cache appears to be 256k. They don't use all the pins in the socket and I seem to recall this was ok because other Cache SRAMs were probably compatible that had more pins.
Click to expand...

There are two types of SRAMs supported in those sockets, the DIP-28 style 32kx8 chips (for 256kbyte of cache, which you have) and the DIP-32 64kx8 chips for 512k of cache. Here's a listing for some, but they're pretty expensive:

www.ebay.com/itm/401214130586

Zippy Zapp said:
3. What is the VRM socket used for? I don't recall seeing this on the other 286 - 486 systems I built.
Click to expand...

The manual specifies jumper settings for the VRM socket, but I suspect there was a proprietary module available for it. Some Socket 5 boards needed a beefier VRM for the later P5 Pentium chips, or the more power hungry 3rd party chips like from Cyrix.
 
Cool. Thanks for the info, it helps a lot.

I have dug out all the needed stuff from my parts bins so hopefully this weekend I can see if the thing even works. Probably have to replace that clock chip/battery through. Looks like the equivalent is a 12c887
 
I finally had some time to test it, had to finish recapping my Amiga 1200 first and since I finished that yesterday i decided to try to hook this motherboard to power and see if it would POST.

I plugged in (2) 32MB EDO 72-Pin SIMMs, a Cirrus Logic PCI SVGA card, IBM PS2 keyboard with AT adapter and a New Star Tech AT power supply that I bought a little bit back. Powered right up and seems to be ok. I haven't attached drives yet but so far it seems to work. Of course it has a CMOS battery dead error message in post.

I next need to find a replacement for the RTC chip/battery combo. It doesn't look like there are any pin headers for an external battery so I will have to purchase one on Digi-Key, I assume. I think I recall they still sell new stock of these. This one is an ODIN OEC12C887A which I believe would be the same as a Dallas 12C887. I forget what the C signifies. Something to do with the calendar or date? Anyone else have any known good sources for these?

I have a new Heatsink/fan combo for the P1-90 because it gets hot without any heatsink. Funny the instructions don't even mention using thermal compound on the CPU/heatsink. I'll use some.

After that I will need an AT compatible case. I have to check my cases I don't know if I have one that will work besides my P3-800 tower.

All in all not bad for $3 thrift store purchase.
 
Zippy Zapp said:
I have a new Heatsink/fan combo for the P1-90 because it gets hot without any heatsink. Funny the instructions don't even mention using thermal compound on the CPU/heatsink. I'll use some.
Click to expand...

Lol, the last CPUs on x86 you could run bare was the early 486 chips under 40 MHz. Pentiums require a heatsink and fan.
 
GiGaBiTe said:
Lol, the last CPUs on x86 you could run bare was the early 486 chips under 40 MHz. Pentiums require a heatsink and fan.
Click to expand...
Yep. It probably had a heatsink when it was being used. But i had it on for about 2 minutes just to test. It was warm but not so hot I couldn't touch it.
 
Pentiums require a headsink, but not a fan. Some chips had a fan but not all. My gateway P5-120 just put a giant blue heatsink over a 120 mhz chip and the only fan was the system fan. I built a Pentium 233 for my grandmother a long time ago and all that got was a heatsink as well. I even have a Slot 1 P3 that just has a giant heatsink on it and no fan and it works just fine. I have even seen some cheapskate system manufacturers use the system fan to duct air over the heatsink of the cpu, sort of killing two birds with one stone. Dell and HP were known for this, and I think its a major cheap skate corner cutting design.
 
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