Have a cheap Compaq SR1901WM which came with 256 RAM.  From other computers laying around, I was able to find other compatible sticks.  The SR1901 has 4 slots.  I now have one 1 gb stick, one 512 stick, and three 256 sticks.  Which combination would give me the best performance and does it MAKE any difference the order of slots in which they are installed?  I RUN Windows XP, no gaming, no memory hogging software, but obviously need more than 256.  Thanks.Hello!

Welcome to CH!

What kind of RAM are we talking about? And, have you tested it all to be working?

FOUND this

on HP's website. You might want to read this.184-Pin DIMM DDR and yes, it all works.  Just didn't know if a certain combination or slot sequence would make a difference or not.  I have heard that performance is better if all the sticks are the same capacity.  If not, I will go with the 1 gb, the 512, and two 256s.I think your idea...1 gig...512...etc...is going to be ok. I don't think it will really matter much on how you place the ram.

Mixing and matching memory is always tricky. I would try the 1 GB in slot #2, 512 MB in slot #4, and the 2 x 256 MB in 1 & 3. The reason for this arrangement is that your board supports Dual Channel memory and you may get Dual Channel from your 2 x 256, if they are closely enough matched.

Would suggest that you run Memtest86 (http://www.memtest86.com/download.html) for at least two passes (overnight better) to verify RAM after your install.

For what it's worth, I have an ASUS A8N-E (similar board to yours) and just recently upgraded RAM to 2 GB because I dual boot with Vista which is piggy slow on 1 GB. Anyway, I am unaware of any performance increase on XP with 2 GB v 1 GB. I don't game or push the system very much. The point is that you may get the best performance with just your 1 GB stick - probably in slot #1; check your manual or go to the ASUS site.

Good luck.

EDIT: Just noticed this: "I have heard that performance is better if all the sticks are the same capacity." This is true with a Dual Channel board like yours. Based on your stated usage, I suspect that the lack of Dual Channel will not be noticeable to you - and you may get a Dual Channel advantage from the 2 x 256. Stability is much more important than performance.Thanks.  We'll see what happens.Please let us know how you make out.He will probably never see dual channel performance using 3 different sizes of RAM...Agreed - bigger question is will it boot and run stable Strange.  I removed the 256 and put in the 1gb.  It would run for a little while, then automatically reboot.  It did this four times.  I then installed the additional 512 with it and it has worked GREAT ever since.May be a problem with the 1 GB module or in the wrong slot - did you check your MB manual to check on the placement of 1 memory module?

Probably be a good idea to run memtest86 with your 1 GB/512 MB arrangement - see above link. This may well save you some grief down the road.