Odd computer memory behavior.

[Msterbeau]

OK, this is beyond strange. Or not.

I have a homebuilt computer. Intel D865PERL motherboard. I just upgraded the processor and RAM. Processor was a 2.0Ghz Pentium 4 and is now a 3.0Ghz Pentium 4 with HT and 800mhz frontside bus. The former RAM configuration was a pair of DDR266 PC2100 256MB sticks and a pair of PNY DDR333 PC2700 512MB sticks for a total of 1.5GB of RAM. I took out the 256 sticks and replaced them with PNY DDR400 PC3200 512MB sticks so I should now have 2.0GB RAM correct? Nooooooooooooooo!! The system shows that the 256MB sticks are still there. ????? I don't think I replaced the wrong sticks. They are clearly different. All the 512MB sticks have a lot more chips (Black rectangles) on the board. Could a 512MB stick actually look like it has less pieces of silicon on it then another one?

I reopened the box and switched locations just to see what would happen. Still only have 1.5GB... Just the location of 256MB sticks changes. Sounds like I have the wrong ones in there but I just don't see how. I've run out of energy to tear it apart and change the RAM again tonight . I'll test it in the morning.

Anyone want to venture a guess as to why this is happening, assuming that I have the right sticks?

[Scary Guy]

I've got the exact same board... no problems with ram here.

The ram on it is dual paging, so you'll want to replace either 1 and 3 or 2 and 4 for it to function correctly with that.

Also it is possible that the ram you got was mislabled at the factory, though unlikely stuff like that has been known to happen from time to time.

[Msterbeau]

I've got the exact same board...  no problems with ram here.

The ram on it is dual paging, so you'll want to replace either 1 and 3 or 2 and 4 for it to function correctly with that.

Also it is possible that the ram you got was mislabled at the factory, though unlikely stuff like that has been known to happen from time to time.

The new RAM is showing up correctly in the system info utility I'm using. I don't think it's mislabeled. If the dual paging function is where the RAM throughput is limited to the slowest speed sticks... I understand that and I don't care that much. (Meaning, I can't afford to replace them all)

[The_Dark]

I think you have the wrong sticks in. Due to density differeances... the number of chips is not a reflection of how much ram is actually there. Also, with a 800FSB.. that 333mhz ram is going to be giving you problems.

[The_Dark]

Acutally, I'm surprised that it boots it all if the PC2100 sticks are in.

[pharoh]

hold on a sec....are you running 3200 ram and 2700 ram?

[pharoh]

Dark beat me to it lol

[Msterbeau]

hold on a sec....are you running 3200 ram and 2700 ram?

Well... that's the idea anyways... Everything I hear and read says this isn't a big deal as long as there are matched pairs. The RAM is just limited to the slowest speed. As for the DDR333... I was reading that it's actually run at 320 to better sync with the 800mhz bus speed.

[Msterbeau]

And yeah... I'm going to run home and switch the other sticks in just in case. I'll snap a few photos of all the RAM too just so you can see what I'm talking about.

[Msterbeau]

Acutally, I'm surprised that it boots it all if the PC2100 sticks are in.

The board supports 266, 333 and 400Mhz... Why wouldn't it start as long as that criteria is met?

[pharoh]

It supports the ram, but that doesnt' mean it can run them all at once, it depends on the processor and the FSB. you should be using the 3200 only, you will most likely cook the 2700 ram if you keep it up, I am suprised it's running at all lol

[The_Dark]

right, like pharo said... The board may support it.. but the 800mhz FSB the CPU has required pc3200. It's going to force your other ram to run at 400mhz... and cook it.

[The_Dark]

You know... there is a reason people like me get paid to work on computers.

[pharoh]

You know... there is a reason people like me get paid to work on computers.

<{POST_SNAPBACK}>

Same here buddy, lol IT GEEKS UNITE!

[Rayne]

It supports the ram, but that doesnt' mean it can run them all at once, it depends on the processor and the FSB.  you should be using the 3200 only, you will most likely cook the 2700 ram if you keep it up, I am supported it's running at all lol

<{POST_SNAPBACK}>

Pharoh is right!

[Msterbeau]

OK... So why doesn't it say anything about this in the Intel docs for the board?

It does list what bus speed should be used with particular RAM speed:

DDR400 = 800MHz

DDR333 = 800, 533Mhz

DDR266 = 800, 533, 400Mhz

Seems like this is saying it's OK to run the different memory speeds together.

If what you're saying is right... someone at the computer store is going to get soundly beaten because I asked about this before I bought.

[Msterbeau]

You know... there is a reason people like me get paid to work on computers.

Spare me the snide comments please. You're generally one who advocates thinking and doing for yourself. As much as I can, I do the same. If I make mistakes, even though I've done my homework... then that's part of the process and I learn from it.

[pharoh]

I think you need to get out the gloves my friend.

All that means is that when you are running an 800FSB and you are running the slower ram, (333 and 266) it will choke down the speed to run it properly, why anyone would even wanna do that is beyond me. But since you have the 400 in there it will force the others to run at that speed, which is bad Juju.

On a side note mark, if you need any help with pc stuff, you can shoot me an IM, I will be more than happy to help you out.

OK...  So why doesn't it say anything about this in the Intel docs for the board?

It does list what bus speed should be used with particular RAM speed:

DDR400  =  800MHz

DDR333  =  800, 533Mhz

DDR266  =  800, 533, 400Mhz

Seems like this is saying it's OK to run the different memory speeds together.

If what you're saying is right... someone at the computer store is going to get soundly beaten because I asked about this before I bought.

<{POST_SNAPBACK}>

[Msterbeau]

I think you need to get out the gloves my friend.

All that means is that when you are running an 800FSB  and you are running the slower ram, (333 and 266) it will choke down the speed to run it properly, why anyone would even wanna do that is beyond me.  But since you have the 400 in there it will force the others to run at that speed, which is bad Juju. 

On a side note mark, if you need any help with pc stuff, you can shoot me an IM, I will be more than happy to help you out.

I'm not in the mood for Mark's comments or anyone elses for that matter.

WHY?? Because most of us aren't made of money, silly man. I read a fair bit before I went shopping and asked about any issues with doing this at the store. Shit... I've been running different memory speeds for a while already. I had very little reason to think it would be a problem.

Can you point me to a document or web site that describes what you're talking about in detail?

[pharoh]

Sorry Marc, I forgot you spelled your name differently, that was meant for you lol. As for a site, give me time, I will find you something, but this is something I have just ran into from awhile ago, back in the pc100-pc133 (Ram) days.

[The_Dark]

I didn't mean it as snide. I meant it as this is a damn confusing part of the process that most people dont need to know. Take a pill or something.

[pharoh]

I'm not in the mood for Mark's comments or anyone elses for that matter.

WHY??  Because most of us aren't made of money, silly man.  I read a fair bit before I went shopping and asked about any issues with doing this at the store.  Shit...  I've been running different memory speeds for a while already.  I had very little reason to think it would be a problem. 

Can you point me to a document or web site that describes what you're talking about in detail?

<{POST_SNAPBACK}>

Also you I need to know if you are using parity ram or non parity.

[pharoh]

I think you need to get out the gloves my friend.

All that means is that when you are running an 800FSB  and you are running the slower ram, (333 and 266) it will choke down the speed to run it properly, why anyone would even wanna do that is beyond me.  But since you have the 400 in there it will force the others to run at that speed, which is bad Juju. 

On a side note mark, if you need any help with pc stuff, you can shoot me an IM, I will be more than happy to help you out.

<{POST_SNAPBACK}>

The last part I was off on, if your mixing slower ram in with the faster ram, it chokes your faster ram down to the slower speed.......But if your mixing parity ram and non parity ram it will not work.

[The_Dark]

I don't think there is a webpage that fully explains this topic. it would required explaining a rather convoluted layering of topics... but I'll give it a shot...

The Front Side Bus of your computer is the data path your CPU is using to talk to your System Memory. It, depending on your CPU speed, will operate at either 66, 100, 133, 166, or 200Mhz. It does this in both directions (in and out), giving you a relative speed of 133, 200, 266, 333 and 400. This is the speed your ram has to operate at to keep up with your CPU. You can run slower ram.. but your cpu has to be slown down to talk to it and you'll still get bottle necks. With moderen Intel's you can run the internal cpu FSB speed out of sync with your external FSB. This would allow you to put the PC2100 ram in with the 800FSB cpu.. Your cpu will even run at it's proper speed.. internally... but your cpu has to talk to your Ram and other external (to it) system components. They wont be able to talk as fast. In affect... it's like having a frontal lobotomy... Inside it will be screaming fast.. with no way to get that fast out.

[Msterbeau]

I don't think there is a webpage that fully explains this topic. it would required explaining a rather convoluted layering of topics... but I'll give it a shot...

The Front Side Bus of your computer is the data path your CPU is using to talk to your System Memory. It, depending on your CPU speed, will operate at either 66, 100, 133, 166, or 200Mhz.  It does this in both directions (in and out), giving you a relative speed of 133, 200, 266, 333 and 400. This is the speed your ram has to operate at to keep up with your CPU. You can run slower ram.. but your cpu has to be slown down to talk to it and you'll still get bottle necks. With moderen Intel's you can run the internal cpu FSB speed out of sync with your external FSB. This would allow you to put the PC2100 ram in with the 800FSB cpu.. Your cpu will even run at it's proper speed.. internally... but your cpu has to talk to your Ram and other external (to it) system components. They wont be able to talk as fast. In affect... it's like having a frontal lobotomy... Inside it will be screaming fast.. with no way to get that fast out.

Thanks for trying Mark, misinturpreted comments aside.

I pretty much get what you're saying... the processor is only able to access RAM at the slower of the two speeds. (Assuming the two pairs are each rated differently.) What I don't get is the prediction of RAM "frying" due to the mismatch. Everything I read says the faster RAM goes slower, not the other way around, which is what you guys seem to be suggesting. Is the problem with the varying clock multipliers that each must use?

For now it's all acedemic. I'll upgrade RAM to match when I have more $$$

So... onto the original subject. I just changed the other RAM into the computer. They WERE the right one's afterall. I forgot to take photos but the were completely different then what I thought was the right ones. Less silicon.. The markings, etc.. everything visually suggested that those were the oldest of the bunch, thus the 256MB sticks. Also... they were out of an HP Pavilion which is where a lot of the hardware for the current computer came from. (I think by upgrading the processor the only thing left from the HP is the DVD drive.) Anyways.. The RAM from that "looked" OEM... Live and learn, right?

The current config then looks like this:

2 512MB DDR400 PC3200 sticks

2 512MB DDR333 PC2700 sticks

System monitor says they're running at 320 Mhz .. which is what I expected based on the Intel support material for the board.

Whether it's "slow" or not.. It feels a lot livlier then at 2.0Ghz. I'll play in Photoshop tonight and see how it feels pushing things a bit. I won't see the difference in RAM until then. Or doing some crazy multi-tasking...

Appreciate the input guys.