[Solved] MSI B450 Tomahawk CPU compatibility

[ikcdab]

I have just built a new system:

MSI B450 tomahawk motherboard
AMD ryzen 5 2600 (without onboard graphics)
Nvidia gtx 1050 GPU.
PSU with 4 pin CPU power supply connector.
Suitable RAM

When I power up, the system appears completely dead, no MB LEDs, no fan activity anywhere. I have had the MB tested by the supplier and it is ok. The GPU has been working previously in another PC. The PSU is brand new. All is see is the power LED on the GPU come alive.

Two questions:

1. Is this CPU ok? The MB manual says that it needs ryzen 5 with Radeon Vega graphics. My CPU doesn't have that, is this a reason for the mb to appear dead? Do I need to use a CPU with the onboard graphics?

2. My PSU has a 4 pin pci plug for cpu power, but the mb has an 8 pin socket. Does this matter? Will the CPU work ok with just the 4 pin plug in the 8 pin socket?

if its not either of these, then what on earth is causing the whole thing to appear completely dead? No life or activity at all, apart from the GPU power LED lights up.

Many thanks

 

[ikcdab]

Thank you for the previous replies.
I bought the psu from Amazon:
Switching Power Supply PSU 600W ATX with 12cm Silent Red Fan / for PC Computer / iCHOOSE

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[ikcdab]

I have also ordered a 4 pin to 8 pin adaptor.
I an waiting for the mb to be returned from the supplier.
What I was surprised about was the compllete absence of any life at all. Not even an led on the mb or any fans spinning up.

 

[ikcdab]

^^That thing is far from Ace. Do yourself a favour and buy a semi decent power supply.

Something like a Bitfenix Formula 450W or Corsair CX/M (Grey label) will power that system. The one you have now is a ticking time bomb.

Why do you say it's a ticking time bomb? Is it not going to work or do you say it's going too blow up?

 

[ikcdab]

Never heard of the brand so probably cheap an nasty and likely to go pop, 650W power supply without an 8 pin cpu connecter screams low quality IMO

But going back to my original question. I connected everything up. The worry was that I only have a 4 pin cpu power connector whereas the mb has a 8 pin socket. Switched on, and nothing. Everything dead. No leds, no fans. All I have is a white led on the gtx 1050 gpu.
Mb has been tested ok. Gpu has been working ok in another pc. I am told that my amd ryzen 5 2600 (no graphics) is ok with the tomahawk b450 mb.
Maybe it is the psu and its downmarket 4 pin cpu power plug. Any other ideas? How else can I test this?

 

[ikcdab]

You have been told correct it will work with your cpu, in the manual it makes no mention of a 4 pin being adequate so it needs an 8 pin plug, you probably could get an adapter but it's not worth the risk as if it blows it could take other components out with it.
Best bet is to test with a psu that has 8 pin (a friends?) or just buy a decent psu as you know the board has been tested.

Thank you. About suggestions for a cost effective psu with the 8 pin cpu power supply suitable for the b450 tomahawk?

 

[ikcdab]

Thanks for the replies and help. I've now ordered the Corsair CX 550m from Amazon. Good price too.
The MB and new PSU should all turn up tomorrow, so will be rebuilding it all then.
My plan is to assemble it on the bench first. MB, RAM, GPU, CPU, PSU and monitor. The switch on and see how it goes.
Will keep you posted.

 

[ikcdab]

Ok, so now I still need some help.
I have bought new CPU, Corsair cxm550. Motherboard has been returned from the retailer and I'm told they have tested it ok. Everyone tells me the mb and CPU are compatible.
I have bench assembled it.
Mb with GPU installed.
CPU and fan installed and plugged in.
PSU Installer. Power connected to mb, CPU and GPU.
Ram (Corsair ddr4 valueselect 8gb 2133mhz) seated.
Switch on psu. I see white led on gpu.
Short out power on pins.
No reaction at all. No fans, no ezdebug LEDs. Nothing. No beeps.
I can press the flashbios button on the mb and I see a red led flash, so I know power is reaching the mb.
What what can I do? Would not plugging in a ssd or case fan prevent booting?

Is it likely that the cpu is dead? But even of it is, why don't I see and ezdebug LEDs?

I'm really stuck now.

Thanks

 

[ikcdab]

Ok so an update.
I decided to do a BIOS update using the flashback+ process.
Downloaded the file into usb. Plugged in usb. Switched on, pressed flashback bios button and we have life. Specifically
1. CPU red ezdebug led comes on.
2.blue/white LEDs under mb come on.
3. CPU fan spins.
4 PSU fan spins.
5. Bios update process appears to run and completes after 5 mins or so.
6. 3 long bleeps. Blue/white LEDs under mb turn red.
I then switch off. Remove usb. Switch back on and we have returned to the original lifeless state....

Help!

 

[ikcdab]

Just use the following components, Motherboard, PSU, CPU and CPU cooler, on the bench, leave the ram out and the GPU, just to see if it powers on, then start adding 1 thing at a time, ie next put the ram in the correct slot on the board which should be the 2nd slot from the CPU, then try it again, then add the GPU, so on and so forth.

The board should still power up even if the CPU is dead, it just wont post and will get stuck on the red CPU debug LED.

However, 1 thing I have to ask, is your PSU connected directly to a mains socket ? or are you using an extension cable ? id recommend going directly to the mains.

Thank you. So some more progress.
System built out of case on the bench. All components in with empty ssd connected. Usb with new bios in bios flash port. This Usb stick also happens to be my windows 10 installation device.
Power button still dead.
Press the bios update button and all bursts into life. Bios updates, system finds windows 10, installs it, reboots itself a couple of times and all is ok. Everything works as normal. I can surf the net, I install chrome etc. All is well.
But if I switch off, then power button does not work.
It's not a case issue, as I have a temporary button and I have also tried starting by shorting out the power button pins on the mb.
I'm really stuck to know what to do next. Why can't I power of all up normally??

 

[ikcdab]

That would make the motherboard faulty, but before we go down that route again, forget the power button, besides that, what are you using on the pins to try and jump start the board ? try something else like a car key or something like that.

From experience of trying to clear the bios on a board using the jumper pins, some things metal work and other things didn't.

Thank you to everybody who has helped with this.
Problem solved, and I am afraid its red faces time. At least I'm admitting it.
Turns out that I was confused by the labelling on the tomahawk motherboard. Two identical sets of pins meant that I was plugging the case power supply (etc) buttons into the wrong set....yes I know.
It was the tip above to use a different piece of metal - i suddenly realised that I had been shorting the wrong set. I clicked the correct set and hey presto!!

I have learnt a lot from this! Thanks again