I just assembled a sweet server.
Dual P3 1ghz
Tyan Thunder LE with SCSI
1 gig of ram.

I have a gig of Crucial ram (4x 256MB PC133 ECC Registered) but my post only shows 512MB of ram.

Is this because of the Dual CPU's? Each gets 512MB?

If I put 2 sticks in, it shows 256MB total. So the ram is either 128's each or the Dual CPU's has something to do with it.

You have 128MB Sticks, no the dual CPU would not caused it to show only 1/2 the ram, now if you had removed sticks and still be able to see 512, then I would say that's the MAX your motherboard supports

So my best bet is, you have 4x 128MB sticks and not 4x256

I'm starting to think so too.
I'll get on the horn with Crucial tomorrow. They are all labled as 256's..... sigh...

It sounds like you have 128mb sticks as I believe the Tyan board supports 4gb of RAM so it shouldn't be the problem.

I have had this exact same problem on several occasions. Answer: Yes, the memory is 256mb modules. Yes, the memory has chips on both sides of the PCB (right?). No, the memory was not programmed for your board. Therefore, the board is only recognizing the chips on one side of the modules.
When you call Crucial, make sure you tell them exactly what mainboard and chipset you using. They can program a set of 4 for you and get them out, or they can reprogram your modules. I originally thought that this problem only occures with Registered ECC memory, but I was wrong. There is some chip makers who are subject to the situation on regular Dimms modules, too.

Well, it turns out that slots #1 and 2 work fine.
I get 512MB with 2 chips now.

Slot's 3 and 4 are not recognizing the ram at all.
Tyan said I should have been able to post with 1 chip in slot 3 or 4, but it just hangs.

Well, that's a shame. It's beginning to sound like a mainboard issue. Are you using Registered ECC memory? If not, is the Error Correction Checking feature enabled in the Bios? That would definately cause the system to hang. Also, some of those boards have a feature in the Bios which says "Enable Support for greater than 512mb?", or something close to that. Make sure the feature is enabled, if it is present.

If the ram was registering at 1GB in the bios, and if you are running linux you need to edit lilo.conf and add the following line, append="mem=1000M"

If you are able to register it in the bios, but not in linux that will fix it.

For reference to assist...

over on 2cpu.com they have a forum, and there are a lot of Tyan users in the Motherboard forum. Great place to find out RAM compatibility and other issues.

P.S. Did you update your BIOS? Sometimes the issue is just the proper detection...

Stephen -- writing to you from his everyday Dual P3-933 box -- 1866Mhz of cranking power :)

Yeah, flashing to the latest did not help. It was a bad motherboard.

www.mwave.com was nice and overnighted a new one to me, and gave an RMA to return the other.

Everything is working as it should now. :stickout

mwave has always been a good place for me on motherboards... I've ordered 8 from them in the past 12 months, had to return 1 and had no problems.