Thanks for joining the Desktop Board community.
It seems to be a problem during integration.
Does the motherboard beep three times without memory?
Did you connect the processor 12V cable?
Make sure you are using straight video cables, no adapters, DVI to DVI or HDMI to HDMI.
Here is more information available to try to sort this out: Desktop Boards — Troubleshooting System No Boot Issues
You give him correct advice for usual cases of non booting systems, but you completely overlook, that the i7 4790 just isn't compatible to the DH87MC.
Don't you guys think that it's time to give the thousands of series 8 board users the support for haswell refresh CPUs?
Best regards from Switzerland
Pik11 (User of three DH87RL)
Thank you for your reply, Allan.
I'm not sure what you mean by integration.
No, I hear no three beeps (actually no beeps at all), neither with or without system memory installed.
Yes, I have connected the 12V processor cable.
Yes, video cables (HDMI and DVI) are straight, and no adapter is used.
I have noticed that the red LED termed "N PROCHOT LED" is on for just a split second, as I turn power on and also asI turn it off. The processor fan runs constantly as long as power is on. Chassis fans (rear and top) do not run at all, when they are set to Low. When they are set to High, the top fan runs, at least for some time, the rear fan does not. Both fans move (very slight jerk) as the system is turned on and off, regardless whether they are set to Low or High.
I have just checked the list of compatible processors for your motherboard model and indeed the processor is not compatible for your board. pik11 was right.
Please take a look compatible processor here: Compatible Processors