photos of sticks please. front&back without heatspreader.

you say sticks of 1GB RDRAM, while possible, I have doubts that you truly mean Rambus dram

edit: added "without heatspreader"

If not pics without heatspreader, give us vendor and model of the RIMMs. That should at least clarify what we're dealing with. Sure this isn't just registered RDRAM? Iirc Intel's chipsets supported ECC, but not registered stuff...

They were used in the Marvel Family of servers, see https://en.wikipedia.org/wiki/AlphaServer

red-ray wrote on 2022-04-29, 20:20:

They were used in the Marvel Family of servers, see https://en.wikipedia.org/wiki/AlphaServer

Dang, those are some nice machines !

though a little bit too big for my bedroom. 😁

weedeewee wrote on 2022-04-29, 20:36:

Dang, those are some nice machines !

They also have multiple AGP slots, as I recall up to 64 ! An ES47 is not that big, but I don't think you can run Windows NT4.00 or 2000 RC1/RC2 on it.

weedeewee wrote on 2022-04-29, 19:01:

photos of sticks please. front&back without heatspreader.

you say sticks of 1GB RDRAM, while possible, I have doubts that you truly mean Rambus dram

edit: added "without heatspreader"

You're more than right to be suspicious.

Here's the reference number: MR18R326GAG0-CM8 (so 1GB/16, 800MHz, ECC)

Attached is the datasheet.

flupke11, Guess you'll have to get yourself a marvell series AlphaServer, like red-ray suggested 😁

any chip id on the 8 pin chip in the middle of the board? Just wondering if it's ... (i forgot) the same I²C/SMBus little ram chip with some module identification information in it. you might try to mess around with it for fun's sake.

Each of those chips is a 1Mbit x 18 (16)-bit x 32 banks chip, so 64 megabytes. 16 chips per stick, 16x64, 1024 megabytes per stick. So, they are legitimately 1 gigabyte rdram sticks.

Here's the chip datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/v … 1869A-GCM8.html

It might be the ECC causing you trouble? Or have you tested the sticks for whether they worked? There's always the possibility that they work despite not being an officially supported size.

Actual chips are CT-9 (K4R761859A-CT9), which are rated at 1066. All the more reason to make this project work.

The SOP8 chip in the middle of the backside has following markings:

U1 C
AT34

Error 0x7CF wrote on 2022-04-29, 21:46:

Each of those chips is a 1Mbit x 18 (16)-bit x 32 banks chip, so 64 megabytes. 16 chips per stick, 16x64, 1024 megabytes per stick. So, they are legitimately 1 gigabyte rdram sticks.

Here's the chip datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/v … 1869A-GCM8.html

It might be the ECC causing you trouble? Or have you tested the sticks for whether they worked? There's always the possibility that they work despite not being an officially supported size.

ECC shouldn't be an issue, the i850e (as its predecessor RDRAM chipsets) support ECC.

From the datasheet of the I850, it seems there is no support for larger modules, let alone the 1GB sticks:

1Direct RDRAM Support
2 Directly supports two RDRAM Direct
3channels operating in lock-step.
4 82850 MCH supports 300 MHz and
5400 MHz RDRAM
6 82850E MCH supports 400 MHz (PC800-
740) and 533 MHz (PC1066-32) RDRAM
8 Maximum memory bandwidth 3.2 GB/s
9(82850 MCH), 4.2 GB/s (82850E MCH)
10 Supports 128-Mb, 256-Mb, and 288-Mb
11RDRAM densities
12 Supports up to 32 Direct RDRAM
13devices/channel for 300/400 MHz RDRAM,
1424 devices/channel for 533 MHz RDRAM
15 Dual-Channel maximum memory array size
16is 1 GB using 128Mb RDRAM technology
17and up to 1.5 to 2 GB using 256Mb/288Mb
18RDRAM technology
19 Supports up to 8 simultaneous open pages;
201 KB page size for 128 Mb and 256 Mb
21RDRAM Devices; 2 KB page size for
22256Mb/288Mb RDRAM Devices
23 Configurable optional ECC operation: ECC
24with single bit Error Correction and multiple
25bit Error Detection 

Datasheets say lots of things. It's possible the 576Mbit chips weren't out yet to test with, at the time of the i850e's release. Have you tested it?

I normally wouldn't be so bullish about datasheets being wrong, but maximum memory capacity is one thing chipset datasheets (and motherboard specsheets, and laptop specsheets) get wrong a lot.

That said, I wouldn't be surprised if it didn't work. Individual chip density is often a limiting factor for what size of stick is supported. But I'm also used to the non-RDRAM world so IDK, RDRAM is weird so I don't know if it's as simple as the chipset lacking the extra address bit.

if 288Mbit is the max supported size per chip, you're SOL since the modules you have, have chips with 576Mbit/chip

Might the i840 give me a glimmer of hope?

if by glimmer you refer to the 11 = Reserved bits of the DDT part, then, yes, a glimmer, though it could easily be pyrite.

Looking at the RDRAM SPD spec the density does not seem to be even included!

What happens if you install two RIMMs, does the system post? Does Windows boot? What if you limit the memory to 1GB (/maxmem=1024)?

From what I remember from back then the Intel chipsets only supported 512meg sticks. There were many forum posts back then about making 1gig sticks work but it never usually got resolved. I know Alpha based system and some Sun systems would take the 1 gig sticks.

red-ray wrote on 2022-04-29, 23:33:

Looking at the RDRAM SPD spec the density does not seem to be even included!

What happens if you install two RIMMs, does the system post? Does Windows boot? What if you limit the memory to 1GB (/maxmem=1024)?

So... I'm guessing, playing around with line 4, 5 ,6 & 100 might give some results... if the refresh doesn't throw any sand in the eyes.

weedeewee wrote on 2022-04-30, 09:26:

red-ray wrote on 2022-04-29, 23:33:

Looking at the RDRAM SPD spec the density does not seem to be even included!

What happens if you install two RIMMs, does the system post? Does Windows boot? What if you limit the memory to 1GB (/maxmem=1024)?

So... I'm guessing, playing around with line 4, 5 ,6 & 100 might give some results... if the refresh doesn't throw any sand in the eyes.

The AP550 (i840) gives me the blinking red light at POST. No VGA output. No difference when using one or two modules.
Idem for the i850e, no POST.

Kindly reminding to you good people that the rdram needs terminators when memory slots are unpopulated.