Installing extra memory seems to make Windows more sluggish

Question

I have an HP Probook 4740s running windows 7 Professional which came with 4GB of RAM.

I just upgraded the RAM by adding another 8GB in the free slot.

However, Windows now takes a lot longer to start up (feels like about 3 times or more).

In addition, applications seem to respond more sluggishly.

Windows (in the My Computer properties) is reporting 12GB of RAM.

I didn't expect that the laptop would be faster, only to be able to run more programs comfortably without swapping slowing it down when switching between them (as I was maxing out the available memory already). I did not expect Windows to perform worse.

Can you think of any reasons why it could hamper performance?

Answer 1

As per Factory Specs

Memory, maximum
8 GB 1333 MHz DDR3 SDRAM

As your have breached this limit by running 12GB I'm not surprised your experiencing performance issues.

Note:

This was a partial answer. I don't know why breaching this limitation affects performance, I just know it does

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Thoughts on this limitation

Hardware limitations on maximum ram capacity is what caused the issue but why?

It would appear that windows could see all the available capacity of RAM but when trying to address certain regions which it believed were available it was failing due to the hardware limitation. As such it was experiencing lagging well trying to search for available segments.

But this leaves a few more question:

• Why did it go past POST when a hardware limitation was breached?
• Why was windows unable to detect the limitation?
• Why wasn't windows displaying errors instead of running slower?

I hope someone with more experience is able to shed some light on why this behavior occurs when the hardware limitation is breached

Answer 2

It is a dual-channel motherboard that you forced into a slow single-channel mode by using 2 different sticks of RAM.
This can severely hamper performance, especially if the sticks have a different speed-rating too.
Single channel-single stick is often a lot faster than single channel with 2 sticks.

That 8 GB limit stated by HP is bogus. Windows wouldn't be able to see 12 if that was the case.
That motherboard (Intel HM76 chipset) should be able to take up to 2x8 GB according to Intel.

HP (and a lot of other manufacturers) are known to "limit" the maximum RAM in their specs if, at the time of writing of the specs, they don't offer those particular SO-DIMMS as an upgrade or option.
Those specs rarely get adjusted if such RAM becomes available later.

That doesn't mean it won't work, unless they specifically programmed the BIOS to prohibit this, which is very rare. (And in that case the laptop wouldn't get past POST.)

Always check the motherboard chipset/CPU specs for the real story. The motherboard chipset or the CPU in 99 out of the 100 cases is the limiting factor when it comes to maximum RAM specifications.