rdram (rimm) info..?

  • The_torst
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Post 3+ Months Ago

Hi guys,

I just bought two 512MB rdram ECC sticks for my HP KAYAK XU800, but it gets a "memory problem" when it boots.

I used to have 2 x 64mb ECC, but it says: 64mb/4, and my new ram says: 512mb/16 - what does the number after the slash mean?

There is also a difference in some weird number, which again, I don't know what stand for:
Old ram: KMMR18R84AC1-RK8
New ram: MR18R162GMNO-CK8

Does anyone know what these numbers are, and why it doesn't work?

Thanks a lot,
Torst.
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Post 3+ Months Ago

  • Tchuki
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Post 3+ Months Ago

Rambus Inline Memory Modules use RDRAM and require a special high speed data bus on your mobo. Due to the high speeds at which they work, they usualy come with heat spreaders.

Unlike other types of RAM, when using RIMM, all RAM sockets must be filled, even if only one is in use for RAM. You can get special continuity modules [ they look like RAM modules but without circuts ] just for this purpose.

With that in mind, I would check to see whether your mobo supports RIMM and perhaps look into getting some continuity modules if you decide to stay with the RIMM.

Quote:
I used to have 2 x 64mb ECC, but it says: 64mb/4, and my new ram says: 512mb/16 - what does the number after the slash mean?


Not posative on this one but I have a feeling it is to do with the number of chips found on the module [ the black spidery things ]. 512/16 may be just stating that the module has a total capacity of 512mb shared between 16 circuts.

Check to see how many chips are found on your 64Mb module, if it is four, then theres your answer. If not, I`m stumped :P

Quote:
There is also a difference in some weird number, which again, I don't know what stand for:
Old ram: KMMR18R84AC1-RK8
New ram: MR18R162GMNO-CK8


They are most propably just serial/product codes, nothing to really worry about.
  • The_torst
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Post 3+ Months Ago

Thanks a lot for that, it makes a lot of sense.

I've got 4 RIMM sockets on my mobo, with two cont. modules. It all works fine with the (2 x 64MB) + (2 x cont. modules), just not with the 512's...

I'm even sticking to the manual here (usually, I don't :) but this was just too weird :P ), and the speeds are the same for both sets (pc800 for both the old 64's and the new 512's)...

Is there nothing else to be careful about when buying RDRAM than size, speed and ECC? Could also be the ram modules..?

Thanks again,
Torsten.
  • Tchuki
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Post 3+ Months Ago

If both sets of modules are running at PC800 then there is obviously something wrong [as you stated ].

The likely hood of it being the modules is slim. The fact that they work [ if being a bit slow ] leads me to beleive your mobo may not support the new modules.

How old is the board and what RAM speeds does it support ?

If you mobo only supports up to a certain speed [ which is not the same as your RAM speed ] then your not going to get the most out of your RDRAM.
  • The_torst
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Post 3+ Months Ago

The mobo supports pc600 to pc800, and since the old 64's, which work fine, are pc800 just like the new ones, there should be nothing wrong with the speed?

Here's a link to the manuals if you want:
http://h20000.www2.hp.com/bizsupport/Te ... esId=65969

I can get ahold of another mobo (same model) to see if mine is just screwed up. I think I got in 1999, so it's 6 years old.. and time for an upgrade :)
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Post 3+ Months Ago

The_torst wrote:
The mobo supports pc600 to pc800, and since the old 64's, which work fine, are pc800 just like the new ones, there should be nothing wrong with the speed?

Here's a link to the manuals if you want:
http://h20000.www2.hp.com/bizsupport/Te ... esId=65969

I can get ahold of another mobo (same model) to see if mine is just screwed up. I think I got in 1999, so it's 6 years old.. and time for an upgrade :)


Sorry, I thought you ment the RAM was only going at PC800 when it should be running at some other speed.

My bad !! :P

So you mean the modules just don't work at all ? Does you PC give out any beeping noises when you have the 512Mb modules installed ?
  • The_torst
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Post 3+ Months Ago

Well, no. No beeing sound at all, and the screen doesn't get any inputs at all. I've got this little nice screen on the front of the computer, giving the status of the whole system. About five seconds after I turn the comp on, it says: "memory error". It looks like nothing can get into the ram at all. Ther screen says that I stil have 2x64 installed, so I tried resetting the CMOS; no difference :cry:
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Post 3+ Months Ago

I`m a bit confuzzled by this. Took a look at the user manuals you provided by link.

Things that we have to eliminate :

You definatly have the RDRAM Expansion board and not the SDRAM
Modules are identical
Modules installed in correct slots [ A0 & B0 ]
Continuity modules installed correctly
Your mobo fully supports the modules you have
HP User Guide wrote:
Use only the HP memory modules provided for your PC model. The use of
memory modules from any previous PC computers is not supported. If you
want to find out about available accessories for your PC, refer to the HP
Accessories Web site at: http://www.hp.com/go/pcaccessories


I also read somewhere on the HP site that some XU800's were shipped with the wrong CRIMM sets [ ones designed for SDRAM ] and have you tried using RIMM Terminators rather than CRIMM's ?
  • The_torst
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Post 3+ Months Ago

Yup, we can eliminate all of these.. The user guide does state that one has to buy all accessories from HP, just like any manufacturer would do :) I didn't buy the ram from HP, but it's the same make as the ones I got from HP (samsung), same speed, ECC just not the same size.

I was lucky enough (for once :) ) to get the RIMM version, not the CRIMM one, if that's what you mean?

At least I'm not the only confuzzled person here :) I'm getting another one of these pc's home in about 4 days, I'll try on that one to see if it makes a difference. It could be the mobo, no?
  • Tchuki
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Post 3+ Months Ago

There is the possability that it is the mobo yes.

By looking through the forums on the HP site, some poeple solved the problem by FLASHing the BIOS.

On the other hand, some people had no luck after this process.
  • The_torst
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Post 3+ Months Ago

How do FLASH the BIOS? Never done it :oops:
  • Tchuki
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Post 3+ Months Ago

It differs slightly between PC's. I would refer to your user manual on how to FLASH your PC's BIOS.

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