Increased memory

[Stanka1]

I installed the Micron MT16HTF25664AY-800G1 memory module in my computer HP Compaq dc7900 Small Form Factor. What happens when I start the computer?

[NonSequitur777]

@Stanka1,

The Micron RAM you specified is compatible with your HP Compaq dc7900 Small Form Factor.

Please specify how your RAM stick/sticks (?) is/are positioned in your desktop's RAM sockets:

Link: https://support.hp.com/us-en/document/c01869333

Kind Regards,

NonSequitur777

[BeemerBiker]

[edit] @NonSequitur777  you beat me to it!

That memory appears compatible with DC7900.  It is banked 2Rx8 which is commonly used.

I compared it to the following vendor who is selling 4 modules for about $22 (if I read the description correctly)

https://www.ebay.com/itm/303317302687

The only problem I can think of is if you have unmatched memory. such as a mixture of different latencies, voltages and sizes.

My understanding is that many HP system have hard coded memory requirements and may not be able to handle a mixture of different modules.  

If the system does not boot there is usually a beep code or the led on the num lock blinks a pattern.  In a case like that I would try each memory stick separately.

Your system has  4 sockets and if you have different sizes or manufactures be sure to put the matching one in the same colored sockets as the color is used to identify paired memory.

[Stanka1]

I have 4 RAM sticks. All is from Micron Technology.

[NonSequitur777]

@Stanka1,

All four RAM sticks are the MT16HTF25664AY-800G1 Micron 2GB PC2-6400 DDR2-800MHz non-ECC Unbuffered CL6 240-Pin DIMM Dual Rank memory modules (4 x 2GB)?

You are set to go.  Since all RAM sticks are the same, you'll have the advantage that your RAM will run in Dual Mode. As @BeemerBiker mentioned, it is best to 'stick' to the very same RAM.

Kind Regards,

NonSequitur777

[Prométhée]

hi @Stanka1 

@NonSequitur777  @BeemerBiker 

sorry but it is not the same subject that comes up every time?

https://h30434.www3.hp.com/t5/Desktop-Hardware-and-Upgrade-Questions/Replacing-DIMMs/m-p/8354275#M21...

[Stanka1]

No. The models are not the same.

Slot #1: Micron MT8HTF12864AY-800E1

Slot #2: Micron MT8HTF12864AY-800E1

Slot #3: Micron MT8HTF12864AY-800E1

Slot #4: Micron MT16HTF25664AY-800G1

[NonSequitur777]

@Stanka1,

So, you have 3 x 1GB plus 1 x 2GB, which is not ideal in my opinion. It should work, even though don't expect optimal performance.

Kind Regards,

NonSequitur777

[Stanka1]

Will my computer work normally after starting it?

[NonSequitur777]

@Stanka1,

I would fit the 2GB RAM stick in slot #1 (the black slot, closest to your processor -see picture I added earlier).

Your desktop should be working just fine.  If not, please tell.

Kind Regards,

NonSequitur777