Question I think I just fried my motherboard. Help!

Sep 8, 2021
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tldr; I plugged a PSU cable labeled "CPU" into 2 slots called PWR1 and PWR2. I turned the system on, nothing happened, and now nothing is turning on again.

I have an old tower https://www.newegg.com/global/au-en/lenovo-ideacentre-300-20ish/p/N82E16883795345
It has an old MOBO (lenovo skybay) and came with a 250w PSU and a gtx 750.
I wanted to upgrade so I bought a gtx 970, a new 450w PSU (CW450)
To connect the new PSU to my old motherboard with had a 10pin and a 4pin psu connection I order a 24pin-10 pin connector that people reccomended (I asked about how to connect a PSU to my motherboard in a couple of posts including This one.

Finally everything arrived and I was excited to game on a far better graphics card. I put in the 970 into the slot and hooked it up to the new PSU using the 2 PCi-e 6+2 cables.
The GPU had 12 holes so i detached the little 2 pin side thingy from both of the PCI-e cables and attached it with 2 6 pin connectors.
I attached the new PSU to my janky motherboard with the 24-10 pin adapter and I attached my hard drive to the bundle of little cables that were attached to the PSU.

I was left with one kinda confusing cable which was the cable from the PSU marked "CPU" it was PCI-e and was 2 4-pin connectors bundled together.
My motherboard had 2 remaining slots, one 4 pin that said "atx 12v" on it and 2 4-pin slots next to each other labeled "PWR 1 and PWR 2"

I attached the PSU cable into the 4-pin slot marked "atx 12v" so that one of the cables from the PSU dangled next to it. I turned the computer on and everything seemed to be running fine, all of the fans were on and the hard drive was humming, but none of the Hdmi ports were sending a signal, including the integrated one.

I tried everything, got new cables, switched between hdm1 and hdmi2. I was sure the problem was that the problem was with how i powered the motherboard. I looked at some threads and most of them said to attach the 8 pin PSU cable into the 2 PWR slots, so i tried it.

Nothing happened. I put the PSU cable back into the "atx 12v" 4-pin connector and now no fans are spinning. <Mod Edit>

Is my motherboard <Mod Edit> is anything else <Mod Edit> @HY am I such a moron. Please help!

PICTURE:
IN GREEN IS THE ATX 12V PLUG THAT WORKED WHEN PLUGGED IN
IN RED IS THE TWO PLUGS THAT BROKE EVERYTHING ONCE PLUGGED IN (BOTH PWR 1 + PWR 2 I PLUGGED IN AT SAME TIME

 
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avg9956

Commendable
Apr 7, 2019
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I was left with one kinda confusing cable which was the cable from the PSU marked "CPU" it was PCI-e and was 2 4-pin connectors bundled together.
CPU and the PCI-E power connector for GPU look similar, which is why it is important to distinguish themselves first with the PSU's manual. They look similar, but are different cables.
The PCI-E power connector is used to power the GPU
The CPU power connector (aka EPS 12V) is used to power the CPU.

Modern PSUs usually have them labeled anyhow with printed text onto the power connector itself to prevent confusion.

I looked at some threads and most of them said to attach the 8 pin PSU cable into the 2 PWR slots, so i tried it.
Always read the motherboard manual first to determine which plug goes where rather than relying on threads, as that design of motherboard is particularly old.

It is highly likely that you may have fried your motherboard.

I think this system is a prebuilt? I cannot ascertain the exact model of the lenovo motherboard
Any chance that you have its motherboard manual?

Generally, when a CPU requires 2 power connectors, it hints that it is a power hungry/powerful CPU. This CPU (Intel Core i7 6700) only has a TDP of 65W, its more likely it only requires a single power connector. The CPU socket is usually located on the top portion of the motherboard.



Prebuilt systems (especially older ones) don't really encourage users to customize them. They lack documentation or don't provide for any thereof and won't tell you which plug powers what part. They encourage disposability to buy a new one rather than customization. If there is no documentation at all or a lack of information thereof, I wouldn't risk upgrading the prebuilt.

Edit: Managed to find the manual for your tower, the Lenovo Idea Center 300-20ish
The motherboard model is on page 30

Surprisingly the manual does not even list those 2x 4-pin power sockets you encircled in red. It may most likely be an old/archaic design. They should have been avoided and it is possibly what could have killed your motherboard.
 
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Sep 8, 2021
29
0
30
0
CPU and the PCI-E power connector for GPU look similar, which is why it is important to distinguish themselves first with the PSU's manual. They look similar, but are different cables.
The PCI-E power connector is used to power the GPU
The CPU power connector (aka EPS 12V) is used to power the CPU.

Modern PSUs usually have them labeled anyhow with printed text onto the power connector itself to prevent confusion.


Always read the motherboard manual first to determine which plug goes where rather than relying on threads, as that design of motherboard is particularly old.

It is highly likely that you may have fried your motherboard.

I think this system is a prebuilt? I cannot ascertain the exact model of the lenovo motherboard
Any chance that you have its motherboard manual?

Generally, when a CPU requires 2 power connectors, it hints that it is a power hungry/powerful CPU. This CPU (Intel Core i7 6700) only has a TDP of 65W, its more likely it only requires a single power connector.

Prebuilt systems (especially older ones) don't really encourage users to customize them. They lack documentation or don't provide for any thereof and won't tell you which plug powers what part. They encourage disposability to buy a new one rather than customization. If there is no documentation at all or a lack of information thereof, I wouldn't risk upgrading the prebuilt.
Yeah I kind of thought this was the case ):

What can I do now? should the PSU, GPU and CPU all be working now, or are they stuffed too?

If they're still working I think I'll buy a new case and MOBO and possibly CPU.

sucks I did that though ):
 

avg9956

Commendable
Apr 7, 2019
399
92
1,790
20
We never know for sure, an electrical damage can do all sorts of things.

should the PSU, GPU and CPU all be working now, or are they stuffed too?
The only way to test these is to install them on a new system to test

Always pays to read the motherboard manual first :) If you're unsure, consult first before plugging things in.
The documentation of prebuilts like these are usually of poor quality, mainly due to translation errors. "Power Connector" on page 30 is very misleading. It does not even attempt to distinguish if its a CPU Power connector.
 
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