Machine sometimes will/sometimes won't POST

[DevonB]

Intel i7 4790K
Asus Z97K/CSM
16 Gigs Corsair Vengeance LP
EVGA Supernova 750 G2
Onboard video only

Not sure what's going on, but for some reason this machine will POST and boot perfectly fine, other times it'll act like it's going to POST, but no video for the ASUS BIOS screen at all. The optical mouse light turns on. The USB devices I notice turn off then on. A FireWire audio interface I have hooked to this gets the signal from the FireWire PCIe card I got that it's attached ok (it'll switch from blinking to solid on the interface.) The hard drive light will blink a few times, then the machine will just sit there. I tried detaching everything from the USB ports and even the video to see if the behavior will change. It's booted a few times when I just had the 15 pin DSUB attached to the onboard video (there is no dedicated video card in this PC.) When I press power, it immediately turns off, but if it has booted, it'll shut down properly, but takes it a second to complete shut down. So overall, it acts like it's starting POST each time, but sometimes video will start, other times not. Bad PSU? I haven't torn into it yet.

D

 

[ICIT2LOL]

Hello Devon mate have you tried safe mode?? if not try it see if you can get a sfc and chkdsk done.

[FONT=Arial, sans-serif]https://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html[/FONT]

[FONT=Arial, sans-serif]https://www.sevenforums.com/tutorials/433-disk-check.html< if necessary include the /f switch and if this does not makeany improvement then just run this switch instead /r in the commandline as per Option2 [/FONT]

[FONT=Arial, sans-serif]Runthese in safe mode and the sfc often best run for two to three runs –you can leave out the /r switch in ckdsk if you feel it not necessary[/FONT]


The other thing I/we want to know is have you ben into the BIOS lately for anything?

By the by could you also follow this please
SYSTEM SPECS


Now before we can help we do need to know what is in your machine so please do this
System Info - See Your System Specs


or either enter the specs of your system in your forum profile the specs will appear when we click on that little box bottom left of the post screen it is for me the preferable option as it is easy. As you may appreciate it is very hard when you don’t know what one is working with for example a diesel or petrol engine.

　(pretyped to save time)



If you can get a stick and put this onto it https://www.hwinfo.com/download.php then we can run this

Using HW Info

PART A:


You can test the volts on the PSU with HW Info



https://www.hwinfo.com/download.php < download the right bit version and close the right hand window select Sensors and scroll down to the power section where you will see what the volts are doing see my pic. In my pic the section (Nuvoton) with VBATT as a dead give away you are in the section for the rail voltages. There are other section titles and one that pops up often is ITE (sometimes the usual one for Gigabyte boards)



Now the voltage on the different rails have to be within 5% =+/- of what is required or the machine will not work properly if at all.


Limits +/- (minimum - correct - maximum)

12v1 = 11.4 - 12 - 12.6v

12v2 = 11.4 - 12- 12.6v

5v = 4.75 – 5 - 5.25v

3.3v = 3.135 – 3 – 3.465v

-12v = -10.80 - -12 - -13.20v

+5VSB = 4.75 – 5 - 5.25v

The Power good signal voltage at pin 8 on the 24 pin plug (grey cable) should be the same as the 5v rail reading/s

See this for the rail voltage info






http://www.tomshardware.com/reviews/power-supply-specifications-atx-reference,3061.html (Section 2.)



The original right hand window shows the machine running and is handy for that but for looking at the components in some detail close it and use the main left hand side panel



FOR OTHER COMPONENTS






PART B:


Open each small square with + in it on the section the components are in and then click on the individual component/s (it will highlight in blue) - in the right hand side will appear all sorts of details including brands speeds and other essential info that particular device. See pic for example.

USE PART A: for the PSU test.

 

[DevonB]

Thanks for all the great ideas, but like I said, my machine doesn't even get through POST i.e. I don't even get to the BIOS screen anymore. It was on rare occasion getting through POST a few days ago, but now it won't even do that, period. Everything looks like it's starting to initialize (lights on certain devices turn off then on, HDD light blinks in a specific sequence) but I never get the BIOS splash screen on the monitor.

Devon

 

[Megahertz07]

Yes, it can be the PS. It can also be a lot of other problems. (bad CPU, Memory, Chipset etc).
Did you overclock?
Do you have a case speaker attached to the MB? If you have, do you hear a POST beep or a more than one?

 

[DevonB]

Yes, it can be the PS. It can also be a lot of other problems. (bad CPU, Memory, Chipset etc).
Did you overclock?
Do you have a case speaker attached to the MB? If you have, do you hear a POST beep or a more than one?

Normally when I build a PC, I do hook up the speaker. I'd have to double check the mobo to see though. I don't hear any beeps, but I don't hear any beeps that I recall when it worked fine. So maybe it's not hooked up. With it giving all the physical signs that it's going to go to video and show the BIOS screen, but it doesn't, it could be multiple things still. Ugh, wish this one was easier.

Devon

 

[ICIT2LOL]

Hmm as Megahertz says mate you should be getting a single beep as the RAM is checked now as you cannot check the PSU by software I would be doing it manually with a digital multi meter see pic/s I take it you have power LEDs on the board that light up when you plug in the mains power??

Anyway the meters are very cheap these days and will give you a reading of the rail voltages these should all be within 5% + or - of the required voltage any outside of that range will cause either the macine not to boot or function at all. See this
Limits +/- (minimum - correct - maximum)
12v1 = 11.4 - 12 - 12.6v
12v2 = 11.4 - 12- 12.6v
5v = 4.75 – 5 - 5.25v
3.3v = 3.135 – 3 – 3.465v
-12v = -10.80 - -12 - -13.20v
+5VSB = 4.75 – 5 - 5.25v
The Power good signal voltage at pin 8 on the 24 pin plug (grey cable) should be the same as the 5v rail reading/s
See this as well https://en.wikipedia.org/wiki/Power_supply_unit_(computer)

 

[DevonB]

Update - Replaced the PSU, no dice. Put the old PSU in, it posted twice, and now won't post again. I will have a speaker with harness in the mail tomorrow to see what the beep codes are (stupid Fractal Designs R4 cases are too cheap for speaker for whatever reason!)

Does anyone have a recommendation for a PCIe/PCI (both would be nice, but rather have PCIe at minimum) motherboard diagnostics card for POST/voltage testing? I see a lot on Amazon, but no idea what to trust, and some take 3 weeks to ship from China, which I'd rather not do.

Devon

 

[DevonB]

Ok, so I've done a bunch more stuff now.

Put back in old power supply (new power supply went to another machine I was planning to replace it in, and that machine works fine with the new PSU, so new PSU is good.)
Installed a speaker so I could hear the beep codes.
Getting a 1 long 3 short. According to Asus, that's video.
Install a (I believe) EVGA 210.
Now get 1 long 3 short, and one trailing short beep. Sometimes it's almost directly after the third, sometimes it delays multiple seconds, then does the single beep. That forth beep sounds slightly different than the 3 short beeps, but not at long as the long beep.
Cleared CMOS. Took longer to boot as expected, one long, three short, one short again.
Pulled video card, put it back in old system I just pulled it from. Works fine.
Boot system again, back to one long, three short.
Pulled both 8 gig sticks. One long, 2 short. Just as I expected.
Put one stick back in, 1 long, three short. (DIMM A1 slot)
Pull one stick, put in other stick in DIMM A1 slot. 1 long, 3 short.
Swap order of original sticks, 1 long, 3 short.
Put in video card into other x16 slot, just to make sure there wasn't a PCIe slot requirement. One long 3 short, 1 short like before.
Pulled video card back out again, still on 1 long, 3 short.

What I need to figure out is what the heck is the beep code when a video card is installed in the PC with 1 long, 3 short, then 1 short? Any ideas? Any other ideas? Diagnostics?

Devon

 

[Megahertz07]

PC Hell: BIOS Error Beep Codes