I recently purchased Two PNY 1Gb ram to upgrade from original 512mb. When I put both 1Gb ram in the slots, the computer will not boot up. When I take one out and put the original 512 back in with the other 1Gb, it boots up fine. This is on an Emachine w6409 which is upgradable to 2Gbs.

If you added another 512Mb RAM to increase the RAM to 1Gb then the new 512Mb memory stick could be incompatible with the original 512Mb or it could be faulty.
Use RAM that is same make and speed as the original RAM.
Remove both RAM and just insert the new 512Mb into your laptop and see if the laptop boots up, if not then the RAM could be faulty.

Some motherboards are only upgradable to their allotted amount that board may only handle up to 2 gigs of RAM which is a shame. But this is the way it is. That is why I always check the board memory capacity before I buy computer boards or RAM for them. The beeps indicate error on the slots for the RAM that is why you can start up when you remove ram one at a time and replace. So use the allotted amount of RAM for that board specification or get another mother board that can handle more than 2 gigs of RAM. Sorry for the loss. Thanks for using FixYa! John

My guess would be that one of the components can not support 2GB's of RAM. Did you try both sticks of RAM one at a time?

Without the computer model and make I can't say if it is upgradable or not. Most are upgradable to some extent. You will need to look for the product description of your laptop on the manufacturer website you may want to download the user manual from them or check the manual you have if you still have it. Yo9u are looking for the max ability of the computer and at the speed and type requirements for your ram. Also, you should know that some companies make Ram of the correct type and class but for some reason will not work in some models. I have Kingston ram 2gb modules that will not work in my Laptop but I purchased Siemens Ram of the same type and it works fine. So it may just be a matter of Ram Manufacturer.

According to the manufacturer, if the rails are of the same type and speed, you should install them in the blue slots to work correctly.

maybe problem is with ur smps or motherboard

The black rectangular chips on the side, or sides, of the ram module are DRAM chips. Dynamic Random Access Memory.

('Chip' is slang term to denote IC, or Integrated Circuit)

Each Dram chip is of a specific size, (or can be said as Amount)
There are manufacturers who make the Dram chips, and then the chips are used by the ram memory manufacturer.

Doesn't matter how the Dram chips are arranged. The ram memory manufacturer could put them all of one side, if they designed it that way.

1.Your motherboard will support, (Use), DDR at 333Mhz, or DDR at 400MegaHertz.
(PC2700 and PC3200, respectively)

2.The ram memory module must use 2.5 Volts.
(JEDEC has set the voltage standard for DDR Sdram at 2.5 Volts, so no worries here. Only time to check this, is if you have some High performance ram, that may be set to use a higher voltage)

3.It must be Non-ECC ram, and Unbuffered.

4.Cas Latency should be 2.5 to 3.0 (Ram Timings)

Short solution?

Computer off, and unplugged from power. TOUCH the metal frame of the computer case to relieve your body of Static.

Handle the ram 'sticks' by the body of the stick, and refrain from touching the gold plated contact pins, on the bottom.

If the 512MB stick is in SLOT 1, remove it. Install the 1GB stick in Slot 1. Make SURE it is seated!

(Slot 1, is the ram memory slot that is closest to the Processor. It is the first ram memory slot that the Processor reads)

Leave the computer case open. (Refrain from putting your hands in while the computer is plugged into power)

Plug the computer into power. Wait 30 seconds. Turn the computer on.

Computer boots up? (Starts)
Okay.
Unplug from power. Install the 512MB stick in Slot 2.
Plug into power, wait 30 seconds. Turn the computer on.
Computer boots up?
You're good to go.

1GB ram memory stick is in Slot 1, and the computer does not boot up?
Incompatible ram memory. Remove it. Reinstall the original 512MB stick in Slot 1.

did you try putting 4 1g stick . instead 2 1g and 2 512?

The specs on the memory are correct, so you purchased the correct type of memory for this motherboard. If your getting no video when you power on with the 1gb stick, I would be willing to bet the 1gb stick is bad. Can you return it and try another stick?

Check your owners manual to see if the laptop will support 2GB of ram. If not you will need to use 2 512mb sticks to get to 1 GB
BPCS