Because of the way the economy is atm, I've decided to inject my dinosaur PC (Pentium 4 2.6gHz, uses DDR2 RAM, has an AGP graphics card which has died - good job there's ebay!) with a bit more RAM and limp along until I can afford a newer system, which I've sworn I'm going to save up for... my Christmas present to myself.

My question is:
This MB has 3 DIMM slots that can handle anywhere from 64 mB to 1 gig. I've bought two 1gig DDR2 sticks and have replaced the two 500mB sticks. Is it smart or even safe to use one of the 500mB DIMMs I pulled out or can you not mix and match denominations like that? The motherboard manual I downloaded for this MSI board was - I'm fairly certain - written by someone who, in every-day life, does not speak English... in any event, no mention is made whether that can be done or not.

With 3 DIMM slots, you should still be able to extra 512 stick with the 2 - 1 gigs you purchased.  IIRC, 2 of the slots require identical sticks, the 3rd can vary.

Yay for HBorre!

Thank you, sir! You have a lot of talents, and your knowledge is quite comprehensive. I appreciate this information as well as the promptness of your reply. Hope you're having a good weekend!

As long as your motherboard  supports it. I seem to recall a memory company with a free utility (could have been Crucial, but I'm not sure), that would show what you had, and what it could take.

Plug it in and see. The worst I've ever heard of or experienced is that it won't boot and you'll probably get beep codes. If it doesn't work one way, you might reverse the order. IIRC, some boards can be picky about what's in slot 1. 

Thank you, all of you, for your fine suggestions. I guess the proof is in the pudding: when the "new" graphics card arrives, we'll see what happens.
Thanks again.

RV, may want to check around.  I think I read somewhere that the RAM system will operate at the slowest RAM speed, that third RAM.  Jan

Which is fine, Plutom, because they all pretty much have the same vintage speeds: they are all DDR2 sticks. Indeed, I think the originals were 400mHz and the new ones are 333mHz. Wonder if they will play together... and in which order I should put them in if they do.

You wouldn't happen to have a link on this info, would you?

Hi RV, I just Googled Ram Compatiblity.  The first page has some great info. Jan

Thanks Plutom - did just that

Lots of interesting discussions. One individual asserts that:

Quote -
To run in dual channel you need the ram installed in pairs. If you have an odd number of sticks it reverts to single channel. CPU-Z is reporting the correct FSB of your system at 200mHz. The ram is DDR (Double Data Rate) Hence it is rated at 400 mHz. The optimum configuration for your system is with pairs of PC3200 sticks running in dual channel mode.

Which to me means that if I have 2 gig the same plugged into the first two slots, and 1 500meg that is different plugged into the 3rd slot - even though there are 3 slots - it's not a good idea to populate that slot because then all RAM will run in single-channel mode instead of dual channel mode

Attached Link: Dual-channel architecture

The question is, do you have a dual-channel capable board? According to this link, MSI dual channel boards do have the differently colored memory slots, though I don't know if that applies across the board (no pun intended) [www.legendmemory.com/modules.php](http://www.legendmemory.com/modules.php?op=modload&name=News&file=article&sid=317)

There's an MSI user group here you may want to check out if you haven't already - though I'm having a problem getting it to load ATM :-)

forum.msi.com.tw

I've reached the limit (very quickly) of my capabilities in terms of hardware trouble-shooting. I thought because the rest of the fans and everything seemed to be making the customary sounds and LED lights were flickering... all except for the monitor wasn't coming on: that the graphics card had finally given up the ghost. However, replacing the graphics card did nothing: things still hum and the monitor still doesn't come on, although it does when connected to other PCs. So... MB? No clue.

Going to take it in tomorrow to people with infinitely more knowledge than I have about this sort of thing and let it become their concern.

Thank you all for your kind consideration of my strange little conundrum.