I can install OS in DELL Power Edge R710

Alastyrov,

Power down the server and remove the AC power. Wait about 20 seconds and then restore the power and boot. Verify that the iDrac finishes initializing.  After that the system shouldn't reboot. To access the optical drive hit F11 at the Dell splash screen, that opens the boot menu. Select the optical and then proceed.

Let me know how it goes.

how to remove the request after reboot "press f1 or f2"

Заработало, спасибо

Is there a message that accompanies the "F1/F2" prompt (fan failure, mismatch, etc.)?  If not, boot to F2 (System Setup) and look for any devices that show as UNKNOWN.  If you don't see any, then disable all SATA ports that do not have anything connected to them.

server sees 16GB of 24GB RAM

The F1/F2 message is standard for all Dell systems, so I'm familiar with the full message ... it signals a misconfiguration of some kind - be it a hardware failure or something (like a SATA port) turned on when there is nothing connected to it (this is the most common reason for F1/F2).  There may be a message "accompanying" F1/F2 at ANY point during POST.  If you don't see a message during POST at any point, then do as suggested and check the BIOS for anything unknown, or simply turn off your SATA ports.

Then your F1/F2 probably is indicating an invalid memory configuration or bad memory then.  Did you populate the memory, or does it still have the configuration that came installed from Dell?  Is memory sparing or any other memory config enabled?

full text mesage "strike the f1 key to continue, f2 to run the setup utility"

Yes -  installed from Dell (dillers)

Dillers??

I would run diagnostics on your memory DIMM's then to determine if you have faulty memory.

I find problem's, it's RAM others slot's,

The end , all worked.

After days of not being able to install an OS. This worked. Tx