pc-3200 RAM in a pc-2400 machine

[whiteybulger]

I have a HP 725n that shipped with 2x 256 MB of pc2700 RAM. The specs on the machine say the front side bus runs at 266 MHz, and that the supported RAM speed is pc2400. The machine supports up to 1GB configured as 2X 512MB.

 

I recently replaced the pc2700 cards with 2 x 512 pc3200 (VS1GBKIT400). The machine works well except for a few video problems. Occasionally there will be artifacts left on the screen after closing a window (e.g., a few pixels from a window border will be left on the desktop). The main problem is the machine crashes when trying to play a DVD. I think these problems are related to the memory swap.

 

Is this due to a speed mismatch issue?

 

If so, can I change a BIOS setting to fix it? Can anyone point me to a web page that describes how to do this?

 

Thanks, any help will be appreciated.

[Yellowbeard]

An HP machine will almost certainly NOT allow the end user to change any important bios settings. However, I recently ran 2 PC3200 sticks in a Compaq (HP) machine that is for PC2100 stock. The best thing I could suggest is to see if HP has an updated bios for your machine. Perhaps a flash would help.

 

Also, is your system using onboard video? If so, does it have an AGP slot?

 

Mike.

[whiteybulger]

Thanks for the suggestion. I updated the bios, but the problem persists.

 

The video adapter is integrated into the motherboard. It shares the system RAM, which I think is the source of the problem. The machine works fine, it just has video problems.

 

There is a free AGP slot. Do cards that use this slot come with their own onboard RAM, or do they share system RAM?

 

I guess I'll just get some PC-2700 RAM. Will the Value Select RAM work in this application (VS512MB333)?

 

Interestingly, the machine has a 266 MHz FSB, but it shipped with PC-2700 RAM, and the Corsair memory configuration utility suggests PC-2700.

 

I'm curious about why the PC-3200 doesn't work. My understanding is that the memory module is driven by the chipset's memory clock. If the clock is running more slowly than the memory module's design specifies, the module just has more time to respond to the signal change. If the clock runs faster than the module, I can see how there would be a problem. Does the module have its own clock that must somehow synchronize with the one on the chipset?

[Yellowbeard]

There are literally hundreds of technical reasons I cannot explain properly as to why PC3200 won't work. My best guess is that the ICs used on the RAM are not suitable for running at the speed the computer is trying to run. The RAM I ran in the Compaq machine is Winbond BH-5 based RAM. The BH-5 ICs are reputed to be some of the most "friendly" ICs ever made and will work across a huge variety of platforms.

 

Any AGP card you buy these days will have its own RAM onboard. You may want to see if you can lay your hands on a card to test before you buy if you have a buddy or whatever that could loan you one. But, going to an AGP card will help both your CPU and your system memory.

 

Mike.

[whiteybulger]

Thanks, Mike!