Asus ROG Strix Z370-E passes CPU, RAM check but no video signal.

[lukejohndeankelly]

Hi everyone, I have been tearing my hair out over this one for the last couple of days. I am building up a new computer and it just will not POST to video signal. Here are the details, I would appreciate any advice...

Hardware currently connected:

- Asus ROG Strix z370-E mainboard.
- Intel Core i7 8700K (supported on all hardware revisions and bios 0420).
- Corsair Hydro H100i v2 all-in-one CPU cooler.
- Corsair Vengeance LPX 2x8GB RAM CMK16GX4M2B3200C16 (found on memory QVL).
- Corsair RM750i power supply.
- Acer Predator 27" 144Hz G-SYNC monitor connected by displayport cable.
- Logitech Pro keyboard connected to USB1 (black) rear port.

The hardware is sitting on the desk with no case, SSD, video card etc. Breadboxing as the kids say. The monitor is turned on in standby mode, it only has a single displayport input. I am starting the mainboard by shorting the two power switch pins on the mainboard header. There is no PC speaker as the Q-LED lights should announce hardware problems instead.

When the power supply is turned on the orange be-careful-mainboard-has-power LED comes on and the strix rainbow lighting also starts doing it's thing.

When I start the computer:

- the power supply fan spins briefly before stopping (the RM750i is meant to do that).
- both fans on the H100i cooler spin and keep spinning, I think I can hear the pump (connected to internal USB header) but not sure as it is very quiet.
- the red LED (CPU test) lights up for about 0.5 seconds before turning off again.
- then the yellow LED (RAM test) lights up for about 1.5 seconds before turning off again.
- the white (VGA) and green (boot, disks?) LEDs do not light up at all.
- then nothing; no video signal, no error lights and no keyboard backlight.

From what I can tell this means that both the CPU and RAM have passed the POST and I cannot figure out what the hell is going on after that.

Here is the troubleshooting I have done so far:

I cannot update BIOS as the Z370-E has no flashback function - need to be in BIOS or Windows to update. Weirdly enough the manual has a section on doing the flashback but searching online confirmed that the mainboard did not ship with the feature. Even so, the 8700K was supported on a very early BIOS version.

The mainboard has been replaced as the first one was (I presume) DOA (did not even light up red or yellow LEDs). No visible damage, cracks etc that I have noticed.

Both 8 and 24 pin power cables are firmly connected to the mainboard. Also swapped in a known-good Corsair RM750x power supply from another computer.

The RAM is installed in the A2 and B2 slots as reccomended by the manual but I have also tried diffrent configurations including single stick. Also swapped in a known-good stick (exact same model) from a different computer. If I do not install RAM the yellow LED stays lit.

I removed the CPU and cooler, inspected for damage on CPU and socket and also checked the spread of thermal paste; everything looks ok. Put it back together cross tightening the thumb screws to medium-finger-tight.

Installed an Asus ROG Strix 1080ti video card and using the displayport on that card in case the onboard video was dead. Removed the video card afterwards.

Tried a different known-good monitor and display port cable.

Tried with no keyboard and keyboard in different rear ports.

Stuck. Stuck, stuck, stuck.

 

[Tolis_GR]

Did you try without the cooler, or at least without that corsair link to the usb header? I was thinking of sorting as this is the only troubleshooting step have you not taken into account.

 

[RememberThe5th]

Clear cmos, then if it still doesnt show up image after booting up first time , press restart once, and thats how it worked for me somehow when my 1050ti didnt worked.

 

[lukejohndeankelly]

Thanks guys, tried without the cooler and clearing cmos a couple of times. I am going to try returning the CPU as it is the only part I have not swapped out yet.

 

[hugogrethen]

I have the exacte same problem as you, i have changed my motherboard with the same model and i still have no display on my screen. I'm goig to change my cpu too to see if it is the problem.... gl for you, and give us update!

 

[lukejohndeankelly]

The replacement CPU arrived and I just did a breadbox setup on the desk - it reached the BIOS first try.

So the two most important parts were dead on arrival - both the original Z370-E mainboard and the 8700k CPU. Interesting that the CPU was healthy enough to pass the basic POST test but not to load the BIOS up. Soooooo frustrating! Thanks for the advice guys.

 

[alex_clk]

I have the same problem with my Asus Strix 1070 video card both my old Asus motherboard and the new ASUS Z370-A II motherboard. The way to fix it is to install the GTX Strix 1070 video card, reset the bios and let it seat overnight with the power unplugged, and it will work after. I am trying the same method on the ASUS Z370-A II motherboard and will update the result.