Question APU will boot but not CPU???

Jul 14, 2019
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I have a new build and I can not get CPU's to boot, there is no display at all. However when I put an APU in it boots up just fine!! I am using Ryzen 2400G, 2600x and 3600 . ROG Strix B450-f Gaming board with the latest bios . Any ideas on why the apu will boot but not either CPU??? Also the same problem when using ASrock x470 sli/ac board except that board turns off and on
 

Karadjgne

Titan
Herald
Simple. Just from what's included. Or in your case, excluded. The cpus do not have an igpu. Exactly no graphical output whatsoever. You need a dedicated gpu with those Ryzen cpus. The APU's have built-in Vega graphics, so do not need external graphics source like a dedicated gpu, to put stuff onscreen
 
Jul 14, 2019
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Simple. Just from what's included. Or in your case, excluded. The cpus do not have an igpu. Exactly no graphical output whatsoever. You need a dedicated gpu with those Ryzen cpus. The APU's have built-in Vega graphics, so do not need external graphics source like a dedicated gpu, to put stuff onscreen
yes I also have a dedicated GPU as well, sorry I knew I left something out. The GPU will still display with the APU but not with the CPU's as well.
 

DMAN999

Respectable
Apr 17, 2019
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with the latest bios
That may very well be the Problem.
A lot of people are having issues with BIOS 2406 and have said that version 2301 works better with the Ryzen 3000 series CPU's.
And for the 2000 Series CPU's BIOS version 1201 (with AGESA 1.0.0.6) works best.

Read this if you want to flash version 2301 to see if it works better for you:
https://rog.asus.com/forum/showthread.php?99490-Flash-any-most-Asus-motherboard-Bios-in-DOS-with-USB-tutorial-Intel-AMD-roll-back
 
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Jul 14, 2019
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And you are positive the monitor is plugged into the gpu, not the motherboard ports?
yes I am positive. The GPU is an R9290....could it be an outdated driver issue??? I am going to update it tomorrow, I just didn't think that should stop me from getting to the UEFI especially when it will let me with the APU installed
 

rigg42

Prominent
Oct 17, 2018
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You probably just need to enable video on PCIE in the bios. Check around in the bios with your APU installed there will be an option for this. Are you sure the video card is good?

Clear CMOS with one of the CPU's installed before doing the above (unless the APU is already Installed) and see if that helps.
 

Karadjgne

Titan
Herald
No. Drivers only affect cards after POST, not before. You should be able to boot into bios even without specific drivers installed, bios is vga and native. Cpus without detected igpu won't be given the option in bios, only APU's will, as to which is primary and which is secondary video output.

If you aren't clearing cmos before swapping, you may be getting a conflict in bios as that video setting is more than likely set to use the igpu from the APU primary. Cmos is a list of bios instructions, so on boot the cmos comes first and skips much of bios functionality. Clearing cmos after cpu swap will force bios to start from scratch and physically discover everything new. Reset does the same function, windows shutdown does not, it saves cmos list for faster boot times.
 
Reactions: rigg42
Jul 14, 2019
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No. Drivers only affect cards after POST, not before. You should be able to boot into bios even without specific drivers installed, bios is vga and native. Cpus without detected igpu won't be given the option in bios, only APU's will, as to which is primary and which is secondary video output.

If you aren't clearing cmos before swapping, you may be getting a conflict in bios as that video setting is more than likely set to use the igpu from the APU primary. Cmos is a list of bios instructions, so on boot the cmos comes first and skips much of bios functionality. Clearing cmos after cpu swap will force bios to start from scratch and physically discover everything new. Reset does the same function, windows shutdown does not, it saves cmos list for faster boot times.
so I reset the CMOS with the 3600 installed, it powers on for 20 seconds and then shuts back down. It repeats this over and over. I reset the CMOS and installed the APU and everything works great! This is driving me nuts!!! lol
 

rigg42

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Oct 17, 2018
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I had trouble getting a 3600 to post on a b450 gigabyte board. It posted twice but was completely unstable and crashed after a few minutes in windows. After that it refused to post with the 3600 installed. I popped a 1600 back in it and re-flashed the bios. It's been rock solid with the 3600 ever since. My Asus Crosshair 6 hero has been flawless with 2 different 3000 CPU's. The post cycling suggests a possible memory issue to me. I couldn't get a 3200 CL 16 kit stable using XMP in an AsRock board although it would post just fine. The kit worked perfect with a 1600 in the same motherboard and also with the same CPU in the C6H.
 
Reactions: arnould1
Jul 14, 2019
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I had trouble getting a 3600 to post on a b450 gigabyte board. It posted twice but was completely unstable and crashed after a few minutes in windows. After that it refused to post with the 3600 installed. I popped a 1600 back in it and re-flashed the bios. It's been rock solid with the 3600 ever since. My Asus Crosshair 6 hero has been flawless with 2 different 3000 CPU's. The post cycling suggests a possible memory issue to me. I couldn't get a 3200 CL 16 kit stable using XMP in an AsRock board although it would post just fine. The kit worked perfect with a 1600 in the same motherboard and also with the same CPU in the C6H.
So yeah, I Cleared CMOS again and only put in one stick of RAM and it booted up. I stuck the second one in and nothing! Both sticks will work if I only have in at a time no matter what configuration I have them in.
 
Jul 14, 2019
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That's progress at least. Rolling back the bios like DMAN999 suggested might be worth a shot.
I'm going to give that a try, sadly easy flash will not let me roll it back, so there is a process using Rufus? does not look too hard. other than the one stick of DRAMM thing, everything is humming along lol. Thanks for all of the help. ill keep you up to date
 
Reactions: rigg42

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