[SOLVED] Sometimes PC takes a long time to post. Suspect a MB-related problem.

[Quiverism]

Before anything, these are my system's components:

• GPU EVGA GTX 980
• MB Asus TUF B360M-E GAMING
• CPU Intel i5 8400
• RAM Team DDR4 8GB T-Force DELTA x2 (both have the same brand, model and size, only the frecuency is different. Old one is 2666, new one is 3000).
• PSU XFX XRT 750w Full Modular.

Everything started a couple months ago when I did a small upgrade to my PC (bought an extra RAM stick and an SSD and did a clean windows 10 install on it). Everything worked perfectly for the first 2 weeks, but out of nowhere my PC would sometimes not turn on unless I cut the power to the PSU for a few seconds. A couple days later I realized it's not that "the PC doesn't turn on" but instead it just takes a LONG time to even post anything.

I don't know if I'm using the the term "post" properly... What I'm trying to say is that it takes almost 5 minutes for the PC to give ANY KIND of visual output to the monitor (though interestingly the RGB on the ram sticks and on the MB do turn on instantly even if everything else doesn't), but once it does the startup process goes super smooth and fast (like I said, Windows is in the new SSD). Other than that... there really isn't any other problems, the PC works perfectly when turned on.

By the way... when I say "sometimes" It was pretty much a 50/50 whether it would take an insane amount of time to give any output.

This is the list of things I tried, but the problem persisted:

• Took everything out (even resit the CPU), gave the case and all the components a good clean with canned air and a brush, and put everything back in.
• Thought maybe the new RAM stick was the problem so I took it out and left only the old one.
• Updated BIOS.
• Bought a new PSU cable (the one i had was pretty old).
• Thought maybe the problem was related to my case, so I unhooked everything case-related from the MB and tried jump-starting the PC with a screwdriver.
• Cleared CMOS.
• I swapped any power cables I had an extra of (XFX XTR 750 is fully modular and comes with some extras): SATA, PCI-E and MOLEX.
• Hooked up the PC to a different UPS and power outlet.

As the days went on I got more worried as the 50/50 chance I mentioned lowered steadily... Got to the point that almost everytime the PC would take a LOT of times to boot.

This is when things get complicated: At this point I thought the ONLY thing I had left to rule out was my PSU, so borrowed my brother's PC. Got his PSU hooked up to my rig and it turned on instantly! I thought this pretty much identified my PSU as the problem, but just to be sure I hooked up my supposedly faulty PSU to my brother's PC... AND IT TURNED ON NO PROBLEM! Honestly I was pretty lost... why would my PSU worked perfectly on my brother´s and not in mine? Didn´t make much sense to me, so I tried hooking my PSU back into my PC... and now it works no problem!? I was at a complete loss, but as long as my PC works I guess I was willing to forget all this.

The thing is... after 2 weeks of this "psu temporary swap fix" the problem has come back, again out of complete nowhere. So yeah... I have no idea what to do now, It doesn't help that the problem is not consistent. My PSU worked perfectly with my brother's PC, so that means it must be the motherboard, right? But then again why would my MB work just fine with my brother's PSU? I don't know what think.

 

[geofelt]

If a motherboard has a problem with ram, it will try a number of setting options to get the ram to wirk.
I suspect this is your problem.
Mismatched ram is never guaranteed to work properly.
Ram should be installed from a single kit.

Run memtest86.
You should be able to complete a full pass with NO errors.

If you get any errors at all, look in the bios to see if there is an option to increase ram voltage. A b60 may not have the option.
If you can, raise the voltage from the default 1.2v to perhaps 1.25 and see if it helps.

Otherwise, you may need to buy a proper kit.