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No power/post - suspect psu

T

Tightirl

Junior Member
Hi there,
Recently my AMD setup stopped working and I decided to upgrade. I got the new Intel processor, the motherboard, and RAM you see listed below. everything was fine with the previous build, specifically the power supply and gfx card im reusing on this build. the CPU was physically broken by a relative (honest mistake and not worth going into).

Anyways after a long irritating installation session, I thought everything wa tos good to go and try to turn on for the first time. Nothing happened, no fans are noises or anything. The only sign of life was an orange indicator LED where I had plugged the Ethernet cord in.

I'm typing this on my phone and I don't know how to bold but I'll point out in a separate paragraph. This motherboard requires not only the 8-pin CPU plug but an additional four pin plug which my 750 cx didn't have.

I figured I would try and beat the system as to avoid buying a new power supply. Thus, I appropriated the proper four pins that I needed from one of the additional PCI Express cables and plugged those in the mobo's cpu2 Port. I wouldn't be surprised if this is the problem but I made sure that it was 12 volts and ground where it needed to be (confirmed with multimeter.)

Thinking it was user error as I'm sure it still is, I unplugged and took out the power supply and made sure my modification hadn't screwed things up. I had cut some of the excess power cords that I wasn't needing as there wasn't much room in the case plus they were just unsightly. There are no stray wires or anything like that.

When I have the power supply removed and I shorted the green power pin to ground, it came on and the proper voltages were at all the appropriate pins, including five volts at the grey wire. However, when I did the same procedure with the other plugs still in (sketchy appropriated 4-pin CPU plug, and video card power plug, and SATA power cable), and just the main 24 pin ATX out, the power supply did not respond.

Figuring there was some kind of trickery or sense pin going on with either psu or mobo I decided to try using a 300w separate PSU, in addition to the 750, with the ground and power pin shorted, to supply the CPU 2 4-pin port on the motherboard. With this strategy, everything all of a sudden came on, but I got no post nor picture on my monitor. The LED light indicating CPU missing or failure was also lit. I suppose it should also be noted, and I find it strange that, everything turned on despite the smaller power supply's Main powerswitch in the off position. Additionally, when I remove the jumper from the ground to green power Pin, everything again turned off.

Trying to make the equation simpler, I tried without the external graphic card and use the onboard instead with the same result. I have tried clearing the CMOS, and I've tried reinstalling the RAM and only using one stick.

Lastly, I don't know if it's relevant but obviously I'm not the expert, I have essentially none of the front panel connectors plugged in. I put in my own switch for the power pins but the speaker pins, reset switch, and power and HDD LED pins remain unplugged.

I think I have included everything if not let me know. Kind of burnt out on the whole things for tonight so that's all I'm going to do for now. This is my first post I hope everything's aboveboard and within the guidelines.

Components:
-Corsair cx-750

-Intel Core i5-9600K Coffee Lake 6-Core 3.7 GHz (4.6 GHz Turbo) LGA 1151 (300 Series) 95W BX80684I59600K

-MSI MPG Z390 GAMING EDGE AC LGA 1151 (300 Series) Intel Z390

-Samsung 860 EVO 250GB

-CORSAIR Vengeance LPX 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 3000 (PC4 24000)

-EVGA GeForce GTX 1070 SC GAMING ACX 3.0

Edit: word choice, spelling errors and clarification. Sorry for the double post, don't know how that happened. I'm not very adept on the mobile platform and have been irritated in a hurry my apologies
 
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Sounds like a tricky one. Take it out of the case to check for shorts. Have the motherboard on an antistatic bag and try it. Failing that reseat the cpu.
 
"PSU Hacking"... not really recommended, btw.

Just buy a more appropriate PSU? A modular one, but one with enough wattage to support two EPS12V 4+4 CPU 12V power connectors? Like a 750W or so? Rosewill Capstone is sometimes cheap.
 
Also, i already have a 750. Buying a new psu is going to be the last step. Just dropped almost five hundred not trying to drop another hundred =\
 
Is there someone you could borrow a PSU from? Or maybe you could order one and return it if it turns out not to be the PSU. Not sure what else you can do troubleshooting wise as you have done all the steps that are usually suggested. You could RMA the motherboard I guess.
 
Great minds think alike. I was thinking of "buying"a psu I'm returning it if I found out it wasn't the issue. Unfortunately I don't have anybody around that I could borrow another known working one from.

in your opinion you think it's the board? I hadn't really thought about it too much yet as I was fearing RMA might be the answer and I've already waited so long to put the bill together. I thought it might be the CPU though
 
Hard to say although cpus rarely fail although I guess some must ship DOA. If I had to bet I'd say PSU, motherboard then cpu in that order. Second thought you said the motherboard indicated missing or failed cpu when it turned on so i'm gunna say cpu, psu, motherboard although as you can probably tell i'm guessing lol
 
Those were my thoughts to a degree. I have been building my pcs since mid 2000s. i, nor anyone i directly know, has ever had anything for up doa. That being said, as you pointed out it must happen. My psu was n just working within the last week on my previous setup, though. Snipping some wires (4 pin peripherals, Sara and a pci_e) shouldn't have broken it and it turns on with the appropriate voltages & is able to power other loads besides my pc.
 
so I got it up and running. Apparently the computer doesn't like it when you try to only use a couple of the PCI Express pins. I'd previously told two of them to power up something separate from the computer and how'd it working fine in the previous build but was unable to power this for CPU pins with four of the PCI Express pins. I ended up opening up the power supply and soldering directly to the board, an additional set of 12 volt lines. Since I couldn't find any more male or female heaters for plug and play, i soldered the other ends directly to the motherboard.

Moral of the story, despite being extremely irritated for about two days, I beat the damn thing and willed it into submission. This is good because I don't have the box and apparently to return things you need the packaging
 
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