does 768 meg ram cause conflict?

What OS are you running?

RAM conflict would happen right off the bat, after the system boots, programs load, then the system will crash. Thats my experience with conflicting RAM.
Added: if it is a bad memory module, usually POST test would pick that up...

In your situation, it sounds more like an application has a memory leak, or a heat issue. But thats just a shot in the dark... If its a memory leak, your system will reboot more often than before (just a hint b/c you removed some ram). If its a heat issue, then it will continue to reboot like before... only time will tell with this one.

hi
IS the OS is old too ? - e.g. Win 98 will not be happy with more than 512MB otherwise as said could be a bad chip try swapping them out
cheers!

such odd numbers. There are some other issues that may come into play though.

A lot will depend upon the board and the type of RAM - you need to get a copy of the motherboard's manual and check it out.

I've an older PC which will take two styles of RAM chips as it was produced during the transition period. I can safely use RAM in one set or the other, I can even put RAM chips in both sets and the BIOS will find and check it all. All will work well until the moment the system the system finds it needs to use the RAM in the chip of the other type, then it has some sort of clash trying to access BOTH RAM types together.

My research at the time revealed the BIOS memory check does each chip individually and totals them. But, the two sets of chips use the same access channels and when the system switches from type A to type B it clears the info on what is stored on the RAM for the type A chips and bingo, system crash. Something in the controller chip instructions.

Another issue that can happen is some boards have RAM in matched slot pairs. You can put a single chip in one slot, you can put a single chip in a slot of the other pair, but when you have two chips in the matched pairs, they have to be the same size and preferably the same model. You can usually tell these as the slots are colour coded to go together. If this is the case you need to check the manual and probably have them in different coloured slots. If no colours it shouldn't matter a damn UNLESS the total amount of RAM or the size of one chip exceeds the parameters for the motherboard.

Yes, that happens, the board can only handle a chip or amount of memory up to a certain size and it crashes if exceeded. I've one older board that will not accept any RAM chip above 128MB in any slot.

Hope I haven't confused you too much.

It is bad practise to fit RAM modules of different values, however we'va all done it successfully and as long as the clock speed is the same on both
It does sound more like one or the other of your RAM modules is faulting but there are many reasons why a pc might reboot unexpextedly

Unless you are running Windows 98 or Me on this system, I would expect that you have a RAM type conflict and not a RAM size issue.

Both Windows 98 and Me will do strange things with more than 511 MB of RAM installed.

The fact that the system is running stable with just the 1-512 MB of RAM installed, implies that the 2 DIMMs are not fully compatible with each other.

Or, you are right near the limits of what the power supply can handle and removing the second DIMM reduces the load on the power supply just enough to make things stable.

As this is a used system, it might not be the physical power supply but one of the voltage regulator circuits on the motherboard.

I know that I mention this a lot. But, it would make sense to closely inspect the capacitors on the motherboard to make sure that none of them are starting to fail. I would also check the CPU fan for spinning freely and the heatsink for dust.

Chas

Windows 98 Has a Limit of 756 MEG that it can use and if you want to add more you need to Tweak the Registry to accomplish the change.

That is the only item that springs to mind with 756 MEG.

But if the RAM is mismatched this can cause things ranging from Timing Issues to BSOD errors occurring. ;)

Col