[SOLVED] DIMM slots 2 & 4 not working. Optiplex 790

[Mcreek12]

Only DIMM Slots 1 and 3 work.
In the image posted below Slots 1 & 3 have ram installed and working.
I can use either of the two or both at the same time. (1 and 3)

however when any ram is put into either of the two slots on the right i get a black screen when turning the computer on. (2 and 4)
I have tried a single stick of ram in each 2 & 4, ram in both, or in all four slots; only black screen.

Removed the CMOS battery for 5 minutes. (did not fix problem)
Have not updated BIOS as its something I do not have experience with.
I checked the date that I'm running and it is older. This was a board that I purchased off ebay, so it could be defective.
Wanted to see if there is anything else, or if BIOS updated is my only option.

The motherboard came from a Dell Optiplex 790.

Thank You.

 

[Darkbreeze]

Put your DIMMs in the two slots that have WHITE locks on the ends. Those are the primary DIMM slots for use with dual channel architecture motherboards. ALL dual channel motherboards for as long as I can remember. More than fifteen years at least.

In this case, the DIMM slot labeling is different than for most aftermarket boards, and you want your memory installed in DIMM 1 and DIMM 2. Even some aftermarket boards label the DIMM slots as DDR4_1 and DDR4_2 rather than A2 and B2.

After moving the DIMMs to those slots, you will want to remove the CMOS battery next to the DIMM slots, which you can see in the picture that says Mitsubishi CR2032, for five minutes. During that five minutes, press and hold the power button continuously for 30 seconds. Make sure the power is off and the PSU is unplugged or switched off before removing the CMOS battery or moving the DIMMs around. Then restore power and power up. Full procedure below.

BIOS Hard Reset procedure

Power off the unit, switch the PSU off and unplug the PSU cord from either the wall or the power supply.

Remove the motherboard CMOS battery for five minutes. In some cases it may be necessary to remove the graphics card to access the CMOS battery.

During that five minutes, press the power button on the case for 30 seconds. After the five minutes is up, reinstall the CMOS battery making sure to insert it with the correct side up just as it came out.

If you had to remove the graphics card you can now reinstall it, but remember to reconnect your power cables if there were any attached to it as well as your display cable.

Now, plug the power supply cable back in, switch the PSU back on and power up the system. It should display the POST screen and the options to enter CMOS/BIOS setup. Enter the bios setup program and reconfigure the boot settings for either the Windows boot manager or for legacy systems, the drive your OS is installed on if necessary.

Save settings and exit. If the system will POST and boot then you can move forward from there including going back into the bios and configuring any other custom settings you may need to configure such as Memory XMP, A-XMP or D.O.C.P profile settings, custom fan profile settings or other specific settings you may have previously had configured that were wiped out by resetting the CMOS.

In some cases it may be necessary when you go into the BIOS after a reset, to load the Optimal default or Default values and then save settings, to actually get the hardware tables to reset in the boot manager.

It is probably also worth mentioning that for anything that might require an attempt to DO a hard reset in the first place, IF the problem is related to a lack of video signal, it is a GOOD IDEA to try a different type of display as many systems will not work properly for some reason with displayport configurations. It is worth trying HDMI if you are having no display or lack of visual ability to enter the BIOS, or no signal messages.

 

[Mcreek12]

I tried your first suggestions only using the white DIMM slots and CMOS reset. Unfortunately I had the same problem. Fans turn on, but black screen. I tried a few different video connections with the same outcome.

I have a few questions regarding the second part BIOS hard reset procedure.

"It should display the POST screen and the options to enter CMOS/BIOS setup. Enter the bios setup program and reconfigure the boot settings for either the Windows boot manager or for legacy systems, the drive your OS is installed on if necessary."

Only way for computer to display the POST screen is with Ram in either of the DIMM slots on the left side. If that is okay, I'm confused with the next step.

"reconfigure the boot settings" I'm unsure as to what they should be changed to.

thanks for your time.

 

[Darkbreeze]

You purchased this off Ebay? My guess is that the board is defective. Either that, or you bent one or more pins when installing the CPU and that is causing the the memory problems.