I have yet to see a PRAM battery fail on an iMac since the G5's. Look for other things unless your date and time are not holding and your printer is dropping off line.
Sorry I am getting old and forgetful:
iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program
Apple has determined that some AMD Radeon HD 6970M video cards used in 27-inch iMac computers with 3.1GHz quad-core Intel Core i5 or 3.4GHz quad-core Intel Core i7 processors may fail, causing the computer’s display to appear distorted, white or blue with vertical lines, or to turn black. iMac computers with affected video cards were sold between May 2011 and October 2012.
The ethernet cables do get old and fail, try replacing it.
I thank all of you for your replies! Come to find out I just needed to reset my PRAM. I googled how to do that and it has been running fine for over 24 hours now! WooHoo! Now I need to trouble shoot my Ethernet port on the same machine. It doest recognize a cable plugged in. When I go to the network setting it looks like its trying but still says cable unplugged. I think it may have gotten fried. I don't want to spend the money on a new logic board. The Wi'Fi still works. Thanks again !
Yes you can, you will need to dissasemble the entire imac, it is in the back of the logic board, close to the ram slots. Coin battery model in most computers PRAM is BR 2032, not CR 2032, the first has better support for high temperatures and different composition aldough both have same volts and amperes.
Imac 27 late 2013 picture https://d3nevzfk7ii3be.cloudfront.net/ig...