Computer only recognizes 1 GB RAM

I'm pretty sure RAM needs to be identical, not just similar. ie. PC4200 Go grab another stick of kingston.

RAM does not have to be identical, but it has to be compatible.

Your two sticks don't work with each other. Either exchange the Kingston for a matching Micron, or buy a matching module for either.

As a note... if one is single-sided and the other double-sided - they won't work together.

I always heard this was just fluff sales men used to sell you pairs of RAM. In any event, I never followed it. OP did you look at your manual to make sure its in the right slots.  My current board wants mine in positions 0 and 1 or 2 and 3 which are not right next to each other and are color coded. My board before was the opposite, wanted them right next to each other.

Nesrie, read!

"two available ram slots"

With a MB that can accept 2GB of RAM, that means 2 1GB sticks.

"I never followed it"... That's for sure. Stay out of the discussion if you don't know what you're talking about.

Down boy down. Relax. Chill out or whatever it is you do that takes you down a notch. You can mix and match RAM.

Only to a certain extent.

You can not usually match single-sided to double-sided, or if the sticks have different controller chips.

The maximum ram the system handles is 2GB with two available ram slots.

 

new pc time 

Not if you can't afford it...

This looks like a common issue for this particular computer. It's come up before in other forums, in this case HP's own forum.

http://h30434.www3.hp.com/t5/Hardware/Machine-does-not-recognize-memory/m-p/45302

This individual thought it might be the display driver. http://support.amd.com/us/gpudownload/windows/Pages/integrated_mce-xp.aspx?type=2.7&product=2.7.5.3.4.3.1&lang=English

Unfortunately, I have very limited experience with integrated graphics and messing around with chipsets. I haven't touched boards with those (IGPs)  since the 90s. However, if your computer shipped with the hardware to support 2GB but not the software to support, pretty lame but typical of a mnf like HP, then it would explain some things. Usually when there is a problem with RAM that is installed properly, you get weird things like boot errors, poor performance and instability, not just well, nothing like its not even reading your extra stick That it can read either stick one at a time suggests, to me, that you're not having a problem with hardware compatibilty.

I'm trying to find more where someone actually notes that this works but I've yet to find it. A lot of people don't go back to forums and report success it seems.

One more thing, PC4200 is not a full name... you have :

PC4200U : unbuferred

PC4200R : registered ( ECC :  extra data byte lane used for correcting minor errors and detecting major errors for better reliability )

PC4200F : full buffered

These type cannot be mixed... since you computer is enough old, maybe the ram use is a PC4200U... recent one in shop are almost always PC4200R with ECC now...

About the one side or double sided, it was true in the past... was mainly related o the number of bank... but now, you can find one side with 4 bank if you wish... number of bank need to be identical...

Ram sell in pairs exist for only one reason... they work good together in interleave mode, these mode speed up a lot the computer...

On some very old computer, bios is not able to use the new ram until it is enable via some jumper on the motherboard... read carefully your manual...

Try this out and see if will see your problem. http://www.crucial.com/systemscanner/index.aspx

If none of the above answers help you might also want to go through the BIOS settings in great detail. Once in a while intergrapted graphics will require you to tell the BIOS how much memory to give to the video subsystem. And in thsee settings may also be something to tell it how much memory there is, or more likely where to "map" this shred graphics memory. See if, for insteace you can tell it that this video memory needs to start at the 2 GB address line instead of the 1GB.

It's a long shot but possible, and as with the HP link above, it is possoble that a newer chipset driver stack and/or BIOS could make a difference. Make absolutely sure that if you try a BIOS upate you get the exact one for your model of PC, and sub-model if applicable. You can brick a PC with the wrong BIOS as surely as pouring water into it while it is turned on.

Do you have a video card you can dfrop in the machine to disable the on-board? That might also be worth a test.

Thank you guys for the responses.  I will try your recommendations and report back.  By the way both ram are PC4200U, one sided and running windows xp.  But it's interested the same issue was reported before in the same computer model.

Last time I checked you can't mix and m,atch RAM. PC-2100 will not work sitting next to PC-6400. Am I wrong about that?

The smartest thing to do is - exactly match what you currently have, or buy everything new with RAM that is recommended by the MB manufacturer.

I have never tried to get sticks of different speeds to work together. It seems like a stupid idea to me. If your system requires PC-Whatever - you get that.

If you (generic 'you' - not you personally) are too stupid to find out what your own computer needs, then you shouldn't even have a computer to begin with.

That said... I also have an HP computer. When I upgraded the ram in my system, the first try went bust - even though the ram I bought was listed as compatible at Best Buy. Either would work, but not together. I had to go to a different brand to get everything to work together. Sometimes it comes down to the infinite diversity/combinations factor of the PC life.

Yeah you can mix and match ram of different speeds but not different types. I don't go around calling people stupid for doing what they want, but it will lower the speed to that of the lowest RAM so there is no real reason do it except maybe during some periods of RAM shortage or when the higher speed cost a lot less... price being the driving factor. What was originally discussed was brand, and while some motherboards have some picky issues with specific sticks, there is no reason why you have to stick to one brand when say your mobo lists it is compatible with dozens. If i walk into a place like Best Buy, yeah, the sales guy is going to try and convince me I HAVE to buy two matching sticks, from them of course, and that's pretty much crap, then again, I don't use low-grade parts in the builds I use, but I've installed RAM in HP, ACER, COMPAQ, DELL and way back when, IBM plus Asus, EVGA and I forget what the other one was, not a main braind anymore. They all mixed brands just fine.

A interesting detail :

http://www.memory-up.com/Memory/HPPavilionPCs15006.html

Your HP Pavilion-PCs a1320n only supports memory modules made with a specific type of chip. Should you find what seems to be the exact same memory modules elsewhere for a lower price, it is very possible that the cheaper memory modules will not work in your system.

So, if your new PC4200U use a type of chip non supported by your HP comp, it will not work...

Similar problem that i have know with my HP Color Laserjet CM1015 MFP... these use EDO ram... but only EDO module made by HP work in it, other are not detected... catch is that the HP EDO ram was 5 time more expensive that other brand !!!

Nesrie I think you may need to do some research. Ecery time I have tried to mix and match RAM of diffrent speed the PC will not start up.

And yes if you want the RAM to work in dual channel mode you must use two matching sticks.

My research is my life experience. IT works. I don't know what to tell you. I have actually done it. I am working on on a laptop right now that has two different sticks of RAM in it. It works fine. No problems. This would probably be a real surprise too, they're not even matching in size!

The dual channel thing is also specific to the mobo, some work some don't. I am not the only one with this opinion either. You can search as easily as I can. I think the you can't mix and match RAM is left over old school think. It was relevant at one point; it's not now.

They are probably the same speed.

I've been building computers for more than 10 years. In most cases using RAM that have two different speeds will not work.Sometimes it works but not often.

Are you suggesting I can use DD2 RAM in a DDR board?

Of course you can use two different sizes. They must be they same speed.

Except he said the new stick will work with his HP as long as it's by itself. If it were truly incompatible, it shouldn't work at all or create errors.

RAM sticks of different speeds will work, within limits, at the speed of the slowest one, so a 500mhz 512MB stick and a 466mhz 512MB stick will give you 1 GB of 466mhz RAM. IIRC, the 'limit' was the whole DDR1/2/3 thing so you could mix-n-match only of the same type, but speed differences within the same type would still work. And, of course, RAM of the same speed but different makers (as in the OP) should always work (the computer I'm typing this on is tangible proof of it).

But yeah, there's also the whole single-side double-side fiasco thrown into the mix as well with notebook RAM, which would be my guess for the OP's problem.

example: most times, you can mix pc-2700 and pc-3200 memory but they will run at pc-2700. of course, both (or all) sticks are ddr.

you can not mix ddr, ddr2, or ddr3. it's almost impossible to attempt since there are very few mobos that have two different types of memory slots and the few that do allow only one type of memory to be used at a time.

Asrock boards tend to do the side by side ram (DDR2 with DDR3), and their manuals specify that you can only use one or the other, but not both. And then some boards had different limits for different speeds at some point, like 8GB at 2700 but 4GB at 3200. The thing I hate about pre-builts is they rarely tell the customer upfront enough information about the motherboard inside. 

I never claimed to be an expert on these things, but I've messed around with different builds (pre-built and custom) to have had this discussion a dozen times with different men and women who build or tinker with machines. There is always some funky ECS board or something that defies the general rule, but I stand by what I said, you can mix and match brands of RAM. Speed, suree, though only real reason to do it is price. Hell at some point even the different brands where just pimping Micron RAM in different skins.

And I still think the OP is running into an unusual situation with his board, not incompatible RAM. Am I 100% sure, no of course I am not. If i had the machine right next to me, I would be trying a few things, but for now I can only make suggestsions based on what I know.

This is correct.