PC will only boot with 2GB ram

[Ewie]

PC was updated from 4GB to 16GB ram over 3 years ago and has worked perfectly since then. I also added a video card at that time, which has also worked.  It was updated to Windows 10 six months ago and has had no problems.

Then 4 weeeks ago it wouldn't boot and  PSU fan started racing with no beeps occurrng.

So after some research and find lots of opinion that it was a power supply issue,  I bought another PSU and tried that.  But I still had the problem of a racing PSU fan with no system beeps.

Next I cleared BIOS, then upgraded to 2.99 then 3.04 with no improvement. Then  I pulled video card and switched to VGA.   In sucession I pulled hard drive (using liveCD in optical drive), then optical drive (after reinstalling HD).  None of these steps had any effect on the PSU racing / lack of beeps.

Finally I pulled both memory sticks.  Finally a clue, as  that caused 5 beeps.  That seems to indicate either bad memory or bad motherboard.

Next I tried one 8GB ram stick at a time in each of the 4 memory slots.  Neither worked and it looked like both 8GB sticks were bad.  

So I tried the 2x2GB ram the system originally came with. 

And here's where it gets weird.  Because when I try both 2GB sticks it won't boot and the PSU races, BUT IT WILL BOOT INTO WINDOWS WITH ONE OF THE 2GB STICKS OR THE OTHER.

This leads me to believe that it either has a bad mobo OR a bad memory controller, which is bult into the I5 CPU.   But that's not the sort of thing I want to guess at by pulling and replacing those items.

Looking on the bright side  at least the PC is able to boot up with 2GB ram.  In fact I'm using that machine to type this and do basic stuff like email.  But it sure doesn't run like it used to, especially with Windows 10's memory requirements.

Any ideas would be appreciated, even if it's  finding out I definitely have a bad mobo or CPU.  If that's the case I'll have to bite the bullet and get a new system.  But I'm still hopeful that there's a fix that hasn't occurred to me.

Thanks.

[mdklassen]

> This leads me to believe that it either has a bad mobo OR a bad memory controller, which is bult into the I5 CPU.   

It's my understanding that the memory-controller is part of the motherboard, not part of the Intel processor.

After all, the processor is compatible with different motherboards from several manufacturers.

So, if the memory controller was part of the CPU, it would need to be "wide-ranging" to interact with different RAM (DDR2, DDR3) running at different speeds.

So, evidence is pointing to your motherboard.

[mdklassen]

> it wouldn't boot and  PSU fan started racing with no beeps occurring.

At power-on, the motherboard runs the POST ("Power On Self Test").

This includes running the fans at 100% of their speed, measuring the temperature of the motherboard, and then, if the temperatures are "low", telling the fan to slow down, and get much quieter.

So, if the POST is failing, the fan will continue to "roar".

If the POST completes, there should be exactly ONE beep.

You might be able to find a replacement motherboard that has compatible sockets for the CPU and the RAM and the power-connector, for less money than buying a complete computer.

[Ewie]

"Intel’s core i3, i5 and i7 processors come with integrated memory controller. A processor having integrated memory controller communicates with the memory directly. This is a departure from the earlier designs of Intel processors, including the core 2, dual core and the Pentium 4 processors, that did not have memory controller and they did not communicate with the memory directly. Instead, the processors communicated with an intermediate agent – a chipset, more popularly called North Bridge. The North Bridge chipset, in turn communicated to the memory. "

http://compare-processors.com/integrated-memory-controller/2225/

That would imply that the CPU can't be ruled out.  

[Ewie]

The two options you listed are:

1. Post fails.

2 Post completes and 1 beep occurs.

Here's what I'm getting (I didn't notice this before).

3. No beep but PC boots into Windows anyway.  Based on this behavior I'm not sure whether Post failed or not.

I can still hit ESC and get into BIOS settings when it starts up.  Also I successfully upgraded the BIOS to version 2.99 then to v 3.04.   So the BIOS seems to work "somewhat".   But it doesn't beep.  Weird. 

Used mobos are available on Ebay for around 30 bucks.  I'm tempted.

[mdklassen]

> No beep but PC boots into Windows anyway.  Based on this behavior I'm not sure whether POST failed or not.

Hearing the "beep" depends on the motherboard using "beeps", rather than "a pattern of blinking LEDs", to notify you.

It also depends on having a "PC Speaker" (usually just double the size of the eraser-head of a pencil) on the motherboard.

Or, some chassis have a very-small speaker, connected (one hopes that it is properly) to some pins on the motherboard.

Probably, if the POST had "failed", it would announce that fact to you, and would have prompted "blah, blah, blah, press F1 to continue booting".

[Ewie]

It used to beep once when I turned it on.  Since this issue began it hasn't been beeping other than when I removed the memory and it beeped 5 times.

Normally I can fix these issues because the expected behavior is well documented.   This isn't expected behavior, at least in my experience. 

[mdklassen]

>>> a very-small speaker, connected (one hopes that it is properly) to some pins on the motherboard.

> Since this issue began it hasn't been beeping other than when I removed the memory and it beeped 5 times.

Is it time to again remove the RAM, and listen for those "beeps" ?

Maybe, a broken or (accidentally?) disconnected speaker is preventing the "beeps" ?

But, if it is not broken (is booting properly without beeping) then "let sleeping dogs lie" ?

[Ewie]

"Is it time to again remove the RAM, and listen for those 'beeps' ?"

Good suggestion.  I did just that and the system beeps 5 times, pauses, and repeats.  There's no problem hearing the beeps when they occur, so the absence of a single beep when it does boot is quite noticeable.  The PSU doesn't race with all the ram removed, if that means anything. 

"But, if it is not broken (is booting properly without beeping) then "let sleeping dogs lie" ?"

Except the dog is lying there half dead -  it will only boot with 2GB ram.  Either 2GB stick works, but not both.

Neither 8GB stick works.  And I even tested the 8GB sticks in another system.  There they boot up just fine.

[Ewie]

So does anyone have a rational explanation as to why my  PC will only run with a maximum of 2GB ram?