First Custom Built PC Ever (that I bought used) ... wasn't built correctLY. Dual Channel not recognized

[Home Theater Dummy]

So I've just made my first step into the PC Master Race. (And still a relative newb to actually selecting parts and troubleshooting custom PCs)

I bought a used Custom Built Gaming PC on FB Marketplace. The seller said that a friend had built it for him.
Got him to throw in a 24" 144hz (1080P) Curved Monitor from MSI on a floating arm. and a keyboard and mouse.

But upon closer inspection I discovered SYS FAN 1 wasn't spinning (back exhaust). Easy enough fix, 3 pin connector was on the wrong pins.

I took that time to reroute cables as the non modular power supply had all sorts of excess in the main cavity of the case.
I didn't notice this before, because the "window" on my side panel is a small acrylic sort of  sideways "V" shape, but the 2 8 gig mem sticks are installed directly next to each other. 
(So not dual channel) They are labeled  DDR4_4 | DDR4_2 | DDR4_3 | DDR_1 in the manual from left to right.

They are installed in DDR4_4 & DDR4_2 and all 16gb show as available.

So with the power off I at first did  DDR4_4 & DDR4_3 boot the computer up and after several boot cycles it finally posted. Ram says that 16 are installed but only half useable.

Ok so Check the Manual... Says:

Quote

For optimum performance, when enabling Dual Channel mode with two memory modules, we recommend that you install them in the DDR4_1 and DDR4_2 sockets.

So I do that.

Same issue when I check "about my pc" shows 16 installed but only half available.
So for now, I have them back in the DDR4_4 & DDR4_2 slots, since at least is available...

Is this something I need to fix with XMP in the BIOS?
This is where my expertise goes out the window. Appreciate even the most kindergarten level explanation thank you.

[PwnyTheTiger]

Have you tried cleaning the RAM slots and the pins on each stick with isopropyl alcohol?

[tkitch]

Use the right most slot, and then the 3rd slot over.

 

Gigabyte went stupid with numbering order.  

[Home Theater Dummy]

18 minutes ago, tkitch said:

Use the right most slot, and then the 3rd slot over.

 

Gigabyte went stupid with numbering order.  

Yes, I did that but had the same result. only half are available.

[tkitch]

post a pic of the RAM (with stickers)

[Home Theater Dummy]

23 minutes ago, PwnyTheTiger said:

Have you tried cleaning the RAM slots and the pins on each stick with isopropyl alcohol?

no. But that does make sense, there is some caked up dust in harder to reach areas. so since those slots went unused, they may need  good cleaning.

[PwnyTheTiger]

It can be a number of things that's the problem here..

 

1: The DIMM slots need to be cleaned

2: One of your RAM sticks is bad

3: One or multiple of your DIMM slots are bad.

4: Random PC bullshittery 

 

Also, if the issue persists I've read switching the sticks around in the dual channel slots can work the issue out.

[Home Theater Dummy]

29 minutes ago, PwnyTheTiger said:

It can be a number of things that's the problem here..

 

1: The DIMM slots need to be cleaned

2: One of your RAM sticks is bad

3: One or multiple of your DIMM slots is bad.

4: Random PC bullshittery 

 

Also, if the issue persists I've read switching the sticks around in the dual channel slots can work the issue out.

1. I'll definitely check that.

2. I would think so too. But it's fully recognized in slots 4 & 2 (single channel)

3. Also likely,  slots 3 & 1 weren't used before... Maybe there is a reason?

4. Likely this. If there was already an XMP profile on the BIOS could that mess it up?

[AndersWSP]

Verify that both ram sticks are actually working.

 

Consider that the previous owner did this on purpose, maybe some of the ram slots are bad. With 1 for sure working stick of ram, test all the ram slots.

 

I'm not aware of any setting in bios to disable half the ram, unless it's reserving them for an onboard gpu, that you don't have.

[Home Theater Dummy]

On 5/12/2021 at 5:22 PM, AndersWSP said:

Verify that both ram sticks are actually working.

 

Consider that the previous owner did this on purpose, maybe some of the ram slots are bad. With 1 for sure working stick of ram, test all the ram slots.

 

I'm not aware of any setting in bios to disable half the ram, unless it's reserving them for an onboard gpu, that you don't have.

Turns out your idea was right.

Neither of those DIMM slots will boot with one working RAM stick.
Not a big deal. Just a bummer I can't fill all 4 if I wanted to (or do dual channel)