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RDram upgrade problem.

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March 6, 2006 12:55:11 PM

HI,
My friend has a Dimension 8200 with 512 PC800 RDram.
He says:
"The FSB is 533 MHz, so I thought, it might support PC1066 and ordered 1 Gig. When I remove old ones and install new memory. It doesn't boot-up. I would think this CPU doesn't support 1066 and return the memory and buy PC800. But strangely, when I keep the old 512 MB PC800 and add the new 1 Gig PC1066, the PC recognizes some of it; it sees 832 MB total memory!!!!! How can this happen?
I tried updating the BIOS and flashed to version A09. Still the same...
Do you think, is there anything I can do to make my PC see the 1Gig? (I am willing to make it run at PC800 speed) Or do I have to return them?
I will give the current PC800 RIMMs to a friend, so they don't have to work together.
Further info:
When I go to BIOS setup and press enter when on the ram, it shows all 4 RIMMs, 256MBs in first 2 RIMMs and 512MBs on 3rd and 4th. It shows following info on screen
__________
Channel Speed 400 MHz
--Rim-- Devices Capacity Type
RIM_1 8 256 non-ECC
RIM_2 8 256 non-ECC
RIM_3 16 512 non-ECC
RIM_4 16 512 non-ECC
_______________

Many people told me, my PC doesn't support PC1066. but this website says it does:
http://www.4allmemory.com/index.cfm?fuseaction=search.m...

Thanks for your help in advance,
Regards,
Oscar"

More about : rdram upgrade problem

March 6, 2006 3:00:40 PM

Dell's can be very picky when it comes to ram. Have you checked Dell's web site. My Intel mv850 requires the 400 speed, 1st generation. 533 was the second generation. You really need to match what your systems has.
March 6, 2006 11:27:22 PM

It says it supports RD1066 because the Dimension 8200 had two versions - one for RD800 and one for RD1066.

You have the DR800 version (because you have RD800 RAM installed). I don't think 1066 is backwards compatible w/ RD800.

As for the strange showing when you put the 1066 in, I'd just say its a fluke thing. It probably recognizes part of it because 1066 does not have to be installed in pairs. You probably stuck a RIMM in the 4th slot too, right? In short, take it out, not sure how that would react to it all, worst case would probably fry something. It would probalby cause some instability in your system as well... :p 

Remember that RD800 does need to be installed in pairs!
You can go to http://www.crucial.com/index.asp and use their system scanner... I think it works. :) 
Related resources
a b } Memory
March 8, 2006 4:16:05 AM

It's a BIOS problem, blame Intel first, then Dell. The BIOS has intentionally been crippled to disable PC1066 operation. I ran across this first on an Intel board, but rather than preventing boot, the Intel board simply issued a warning.

Intel decided that PC1066 wasn't ready for mainstream use yet, and instead required mutant memory in the middle, called PC800-40.
a b } Memory
March 8, 2006 4:17:01 AM

Nobly, PC1066 and PC800 are the same thing physically, the Dell is simply crapping out because it was designed to do so, based on the SPD values of the RAM and nothing else.
March 8, 2006 6:36:03 AM

I have little practical experience with RAMBUS (*shudder*) but here's something to try, given the responses here:[*:c266553d4c]Boot into the BIOS config utility with just the slower RAM.
[*:c266553d4c]Tell the BIOS to ignore the SPD, program the timings and frequency in manually, and don't be agressive. Hopefully the config utility will actually let you do this.
[*:c266553d4c]Install the other memory (with the expectation that it will run, but at the slower speeds).
[*:c266553d4c]Cross your fingers.
March 8, 2006 5:07:13 PM

Thanks, I stand corrected. I was confusing RD1066 to the 4200's. Blah, that's what I get for working on 4 yr old memories. :D 
a b } Memory
March 8, 2006 7:28:18 PM

Yes, well, you can blame litterally hundreds of sources for your confusion!

The names RIMM4200 and RIMM3200 were intended to prevent confusion between them and PC1066/PC800. But several sites (unfortunately including THG) used the wrong naming scheme in at least some articles, and VENDERS DID THE SAME!
March 16, 2006 3:43:42 AM

Jesus.. you've got some really bad advice there!

Here's a few things....

1 (nobly "It probably recognizes part of it because 1066 does not have to be installed in pairs. "). If you're using 16-bit modules. Whether they are 600Mhz, 700Mhz, 800Mhz, or 1066Mhz, they will be installed in pairs.

2 (Crashman "Intel decided that PC1066 wasn't ready for mainstream use yet, and instead required mutant memory in the middle, called PC800-40.") - In fact, it wasn't really a decision, it was easier for them to implement the 200x4(800Mhz) FSB then it was the 1066Mhz BUS. Later, the 533Mhz flavor was added as a "high performance" option.

3. (nobly " I don't think 1066 is backwards compatible w/ RD800.") - It is, assuming that the MB recognizes it.

4. "The MB isn't recognizing the SPD values" - Basically, yes, this is probably your issue. Are you sure you're putting them in the correct slots? On some motherboards, this is Slot 1 and slot 2. on others, it is slot 1 and slot 3.

5. "It only recognized 832MB of ram" This is because the Northbridge on your motherboard, coupled with the rsc's on your modules is design-limited to the amount of RAMBUS devices it can access. You see this number for several reasons, mainly the location of the RDRAM in the slots, the speed of the ram, and the amount of devices on each module.


In short... I really would double check to see if you have them placed, and configured properly. If so, then your motherboard is not equipped to recognize the modules.

Blame Dell for not providing a new enough BIOS update because it had probably written off it's rambus boards because intel quit supporting the technology. Blame Intel for canning Rambus technology because it couldn't make FSB speeds fast enough to keep it happy, blame Rambus for suing the semiconductor industry, and blame the semiconductor industry for illegally using Rambus's patented technology.
a b } Memory
March 16, 2006 4:40:26 AM

Yes, well, the mutant memory requirement still stood, I'm fairly certain PC800-40 was required instead of the more common PC800-45 because Intel tightened the timings a bit when 533 bus P4's were used.

Anyway, it should have been PC1066, and most retail boards did use PC1066. Further, I did have an Intel board with PC1066, the BIOS update allowed these to work together but gave me a configuration warning whenver BIOS was reset, a "PC1066 is not recommended, use at your own risk" kind of thing.

Anyway, it wouldn't surprise me at all if Dell simply never introduced a BIOS with PC1066 compatibility. After all, Dell wants people to buy their parts from Dell!
March 16, 2006 4:41:38 AM

um does RDRam need matching pairs for dual channel AND terminators for empty slots?
a b } Memory
March 16, 2006 4:46:21 AM

16-bit modules (PC800 and PC1066) require matched pairs only when used with the i850E and similar P4 chipsets. Plus terminators in the empty slots.

I've heard 32-bit modules (RIMM3200 and RIMM4200) are self-terminating.
March 16, 2006 12:47:24 PM

"I've heard 32-bit modules (RIMM3200 and RIMM4200) are self-terminating."

yes :-D

It would be more appropriate to say that instead of having 2 16-bit modules per channel, RDRAM puts both 16-bit data paths of the channel on one 32-bit module, with both the passthrough and the terminator on the module. In MOST setups, you still needed a C-RIMM (continuity) in the empty slot if you didn't use it.

The SISr659 would have alleviated this need however.
!