New build won't POST

PaxPsychosis

Prominent
May 2, 2017
3
0
510
0
Hi,

We're trying to build a new PC at work, and we're having problems.

Key specs are:
Gigabyte GA-Z170-HD3P Motherboard
I7-7700 Kaby Lake 3.60GHz CPU
Corsair Vengeance LPX 16GB (2x8GB) DDR4 DRAM 2133MHz C13 Memory
EVGA 600W White Series 80+ Power Supply

We plan on using the on board graphics, so don't have a graphics card.

We have the secondary ATX power connected to the motherboard, along with the large power connector.

We built the PC fully but it wouldn't POST... the power LED would come on and the CPU fan would spin, but no video output on the VGA, DVI or HDMI. It appeared to reset periodically every 20 seconds or so as the fans would slow momentarily and we could hear a change in the PSU.

Interestingly, the case has 2 fans in it and one would spin but the other one wouldn't spin. We swapped their connection to the motherboard over, and the fault seemed to be on the output from the motherboard... one of the fan outputs didn't seem to power the fan connected to it. On power up, the fan that doesn't spin will "twitch" slightly a few times, and would twitch again on the ~20 second periodic self reboots.

We stripped the PC right down, and just tried running the motherboard+CPU+RAM on a bench with the EVGA 600W PSU, but we had the exact same result. I borrowed a PSU from a working PC (650W) and we still had the same result, so I'm fairly sure it's not the PSU.

I tried just one RAM stick, in different slots, and no difference.

I connected an 8 ohm speaker to listen for any beeps, and we got 5 long beeps... read around online a little and found a suggestion to re-seat the RAM whilst pushing down hard on one side (where there is no clip). This has solved the beeping and resetting, but now we get zero beeps and it just stays powered on without resetting itself... no video output, no beeps and so I guess no POST.

We took the CPU off and I checked under a magnifying glass and I'm fairly sure there are no bent pins on the socket... it all looks clean and the thermal paste all looks fine. Put it back and still nothing... CPU fan spins but no video output and no beeps.

Any suggestions as to what we could try next, short of RMAing things? The fact that unseating the RAM gives us beeps makes me think the motherboard has some life in it still maybe? If we do have a DOA component, would it likely be the motherboard or CPU?

Thanks
 

Barty1884

Titan
Moderator
The Z170 board likely needs a BIOS update to support the KabyLake i7-7700K.

You'll either need a compatible Skylake CPU (cheapest Celeron, for example) or a local computer store should be able to flash it for you.
Otherwise, return it & get a Z270 board.
 

PaxPsychosis

Prominent
May 2, 2017
3
0
510
0
Ahh, thanks for the fast replies! I'm not sure about the BIOS... any way to tell the version without the CPU installed? I see now on the Gigabyte website we need the latest version.
 

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