ram slot not reading

What CPU? What is the model #(s) of the DRAM? What CPU cooler

If you say both memory sticks of 4GB capacity both work in memory slot one of the board.
Then you should check in your bios if you have the option to change your memory mode manually from single channel mode to dual channel mode. Set it to dual channel memory mode if it is sat on single channel mode.
Save the settings before you exit your bios.
Power the system off.
Then place your second stick of memory back in the second memory slot of the motherboard.
Power it on and see if it boots.

If it still fails, then you should take a look at both memory sticks, making sure they are a matched pair of memory modules.
And the speed of both along with the memory timings and voltage match.
If they don`t then you need to place the lowest rated memory speed out of the two stick of memory in the first memory slot of the board. and the faster one in the second.

Also check if the memory has an XMP mode, if so go back into your bios and check that the XMP option for memory is enabled in the bios, along with dual channel memory mode enabled also.

save thoes settings again before you exit your bios.
And see if the system posts, or boots.

If you have no joy it suggests that one of the memory slots of the board is damaged, or the memory controller of the motherboard is damaged in some way.
Make sure the slots are clean and free of dust and any objects are not covering or blocking the gold pins on the inner side of the memory slots of the board causing improper connections.
And that you make sure each memory stick is locked in place fully in the two memory slots of the board.
And sitting level and flush in both sockets.
Clean the gold fingers of each memory stick with mentholated spirit, or any quick evaporating cleaning, and de grease liquid.
or use a rubber, eraser to de grease and get rid of any dirt covering the gold finger contacts of each memory stick both sides.


Then try them again in the memory slots of the motherboard.

If all of it fails then presume the motherboard has developed a fault on one of the memory sockets of your motherboard.