older PC windows 7 and windows 10 - used to boot fine and won't Post

[TerminusEst]

Hello everyone, having very odd issues with a secondary PC, been putting my own PC's together for over 20 years. I have replaced the 1) PSU 2)GPU 3) Mobo button cell battery 4) sata to mobo cables to HDD's (1x ssd and 1x 7200 rpm hdd) 5) sound card. I can't get the PC to post. After leaving it off a few hours or next day it won't turn on. The only thing that seems to work is resetting the CMS on the Mobo and pulling the CMS battery out. I have to do this every time it doesn't want to start again.

I was thinking it might be the boot devices, so recently I unplugged my DVD writer and SSD and tried running it on just the old windows 7 7200rpm hdd. Seemed to work, my plan was to format the SSD and make a clean install of windows 10 on that. Alas the PC doesn't even boot again today. Wondering if it's a BIOS setting I might have turned off or should turn on, does it matter what Serial ATA connection I plug the main HDD on ?

System Spec
-----------
Computer type: PC/Desktop

OS: Microsoft Windows 7 Ultimate 64-bit 7601 Multiprocessor Free Service Pack 1

CPU: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz

Motherboard: ASUSTeK COMPUTER INC. Z97-AR

Memory: 8.00 GB (2x4) Kingston HyperX Beast Memory
16.00 GB (2x8) Corsair "something" Memory

Graphics Card(s): Nvidia GeForce RTX 2060
(older GPU works fine but swapped out about 8 months ago)Sapphire Dual-X R9 280 Graphics Card - 3GB GDDR5, 384-bit

Sound Card: Sound Blaster Audigy Fx

Screen Resolution: 1920 x 1080 x 64 bits

Hard Drives: Seagate 2TB Barracuda
Hard Drives: Kingston A400 480GB SATA3

 

[file3456]

Memory: 8.00 GB (2x4) Kingston HyperX Beast Memory
16.00 GB (2x8) Corsair "something" Memory

If I'm reading this right, it looks like you're mixing memory manufacturers. If so, just keep one manufacture like the Corsair and pull the rest. You never, EVER mix memory types and manufacturers. EVER! This very well could be your issue.

If you want 16GB it has to be all of the same type of memory. Right down to their serial numbers. Believe me...

Corsair and Kingston are two different manufactures.

What's odd about how different memory manufactures (and speeds, etc) aren't compatible with one another is that there are only 4 or 5 flash memory manufacturers in the world. Then the RAM stick is created by a whole slew of other manufactures that use one of those flash memory chip manufactures.

Off the top of my head, some of the the flash memory manufactures in the whole world as of this post are: Crucial (USA), Samsung (South Korea), Hynix (South Korea), Intel (All over hell)

 

[TerminusEst]

I'm sorry but I've put together over 8 computers every 3-4 years over the last 23+ years. This pc we are discussing has been using mixed memory over 10 years maybe more. I have never had issues with this, pretty sure this is not the reason for the current problems, but will test it again with only 1 stick of ram, ty.

 

[maxseven]

Dunno how to help you TE but am IN because I have had similar issues to your own. You only leave yours off for a few hours--in my case I would leave now TWO computers off for months at a time, and then have problems getting them started again upon my return (from vacation house to fulltime residence). Clearly in my case "months at a time" is not good because of the possibility of CMOS battery death, but it seems like the issue is more than that.

 

[townsbg]

Post usually has audio codes in the format of a long and short combination that can indicate the issue. Try to recognize the pattern and google it based upon either the computer make and model or the motherboard. You didn't provide the make and model so I can't be more specific than that. If you have a manual that might also specify the error. Also I agree on the memory possibility. Try removing the sticks for one or the other manufacturer and see if that resolves your problem. It's also possible that the memory went bad. The post code could indicate a memory error. You might see if the computer will boot into a memtest86+ disc. If so test it using the long test running for several hours.