Question New build, duff CPU?

[Muggit]

Hi

I've just started building around an i7 8700 with all new components (apart from working PSU) and can't get a video output

At present, I've got the motherboard, ram, CPU and PSU connected (as well as USB keyboard and mouse and monitor via Display Port)

When I try to start system, the CPU fan starts, stops, starts again, about 1 second delay for each, and just continues until stopped manually.

I plugged a case speaker in and sometimes I get a short beep followed by another 5 seconds later, but not every time.


I've been able to try two motherboard (ASRock Z390 Phantom ITX, and a Gigabyte Aorus Z390 I Pro WiFi)

Both boards exhibit similar problems although I've not had any speaker beeps from the Gigabyte assembly

I've tried two sets of RAM, both Ballistix 'Sport' , 2666 and 3200, both brand new ( bought for the build)

The only things I've not swapped out yet are the PSU (Corsair SF600) but that's out of a working system, and it's been back in the old system, between motherboard swaps

So, is the CPU dead or is there a chance the PSU isn't up to the job?

Thanks in advance for any advice - I've built several PCs before this one and they've all gone well

 

[Darkbreeze]

Double check that the EPS (ATX12v1)12v power connectors to the motherboard are installed and seated as well as unplugging and re-seating the ATX connector.

I'm going to assume that you are using the correct cables for that PSU, and not trying to use cables from another PSU, because if you are leaving the cables for that PSU attached to the other system and using other modular cables to try and run this system, that's a problem, and has probably resulted in killing both motherboards.

 

[Muggit]

Many thanks for the suggestions, it turned out to be an issue with the DisplayPort - the old mobo, cable and monitor were fine, but when using the new board, there was no video.
I only found this out trying to get an HDMI output.
Once I swapped out the Displayport cable, everything was fine.

Are there different DP cables?
The one I had to replace I'd used for years, and it still works on the old board and another monitor, just not the current combo

 

[Darkbreeze]

Nah, well, yes, there are, and that CAN be a problem, but usually when a cable is the problem it's because there is something broken inside the cable or there are bent pins on the ends.

Often, cables might get bent back and forth or run over constantly by chairs, although that normally wouldn't apply to display cables. This spotlights the reason why cable quality matters. Poor construction could result in anything from wiring to pin connections breaking inside the plug to bridged solder points. I suspect unplugging and plugging in is enough for an existing problem to become prominent whether it's due to a defect or the bending of a pin when not inserted correctly.

Certainly though if it is a very old DP cable, it might have incompatibility issues as well. At least it was a fairly inexpensive fix. This is usually one of my first things I recommend checking on no display issues, but you never came back to discuss it so we didn't get the chance for that.

 

[Muggit]

The cable's now in service on another PC and working fine, it just won't work with that Asus board.
I originally 'ruled out' the cable as it worked when I rebuilt the previous PC back into the case between breakdowns (component and mental )

There's still a couple of weird issues with the build - no audio thru monitor headphone socket via HDMI cable (despite it working on old mobo and settings suggesting it will work), but I bought a 3.5/3.5 cable so that's not a big deal, just a extra wire.
Otherwise, it's working nice