Good day Toms Hardware community.
My problem is simple, but it might be hard for me to explain. I have two PSU’s that I know both to work (they both work in old PC), but only the cheap one works in the new build. By ‘work’ I mean I can get fans/noise/lights/etc. By doesn’t work, I mean nothing, no light, noise or fans. They are both fully modular and I have swapped the PSU’s several times and consistently get the 450w PSU to work and never have got the 750w PSU to work. I need the 750W PSU to work in my new PC because I plan on maximizing CPU overclock and running a 1080TI.
I built a new system and plan on reusing the PSU and GPU from my 2015 build. I have built the 2015 build back up so I have 2 pc’s and am able to independently test and isolate components.
The cheap 450w EVGA PSU works in both PC’s. The nice 750W EPS rated Corsair RM750i works in the old one, but not in the new build. I have tried the new 24pin, 8pin CPU, and VGA cables as well as the original ones from the old PSU.
To reiterate: My new computer MSI motherboard gets power with 450w PSU. The PSU is fully modular, so I unplug everything from the back of the PSU swap and the to the 750w PSU, which does not give power to the mobo when I hit the power switch. I don’t touch anything else, and the cables are all still plugged in the same way to the board, GPU, sata fan hub, CPU 8 pin, etc.
My question is, how could the motherboard possibly see a difference between these two power supplies that I know to both work?
edit 18SEPT2018- Last night was going to attempt to load windows using the 450w PSU, however I couldn't get power (lights, fans, noise), which is just like the other 750w PSU that I want to use. This marks the first time I couldn't get that PSU to work, and I am not sure what changed. I took the parts out of the case to bread board, and I was back to where i was when I made the post - I get power with the 450w unit and not the other one. Now I check the power supplied with the power supply tester. The EVGA 450W unit tests out, see pictures linked below. When I powered up the 750w Corsair psu, I heard a loud arc, a puff of smoke, and the wires were noticeably warm near the woven cable sheath (all events were on the CPU 8 pin cable). But.... nothing else seemed to happen. The power supply tester still gave me results, only notable thing was the 2nd 12v rail was not reading. I spend the rest of the evening reading. This particular power supply is designed to be single rail by default, but configurable to multi-rail. I plan on rebuilding my old 2015 pc with this PSU and logging into corsair link to customize the rail options to make sure all the rails are good. https://i.imgur.com/yhbp8vk.jpg https://i.imgur.com/tbmfaIN.jpg https://i.imgur.com/S2P6KiX.jpg https://i.imgur.com/yjE1TlB.jpg
Edit 19SEPT2018 - I think I found the problem and the source of the inconsistencies and strange behavior. The ATX 24pin both board plug is obviously very standard, however what I did not know is the PSU side of that cable connector plug can be a proprietary pin-out subject to the PSU manufacturer. I said I kept all the cables (fully modular) with the case and only unplugged the PSU side to swap power supplies to troubleshoot problems, which was a no-no. I noticed the 18+10 pin PSU side of the ATX24-pin plug was different between the two manufacturers. I loaded into BIOS last night with all the new parts, so my new rig seems to be okay. The old rig might have some problems, I'll have to spend some time with it.
I suspect this is an issue between my motherboard and PSU, so here are OEM links to them both.
https://www.corsair.com/us/en/Power/Plug-Type/rmi-series-config/p/CP-9020082-NA
https://www.msi.com/Motherboard/B450-GAMING-PRO-CARBON-AC/Overview
New systems that shows the reused parts (Corsair RM750i PSU and GTX 1080Ti)
https://pcpartpicker.com/user/Ulvinator/saved/Dr2xGX
2015 build has the following parts, after I rebuilt it with a new cheap PSU and old GPU.
https://pcpartpicker.com/user/Ulvinator/saved/7K98YJ
I have completed this this and address all issues that would prevent me from getting power (I skipped the steps that might prevent post or boot, but are unrelated to power). Notes below.
http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems
1) I read the manuals
2) The motherboard has an 8 pin CPU plug, and also a separate 4 pin CPUpower2 plug. This 4 pin plug should be unnecessary (at least until its overclocked), but I have tried both PSU both with and without this additional plug.
3) Standoffs are appropriate, pictures of case and back of board attached/included.
4) Yes, I get power with 450w PSU.
5) Yes, many times. New and old cables.
6) Yes, neither stick works, but this wouldn’t prevent power.
7) Yes
8) Yes
9) n/a
10) yes
11) I bent 2 pins slightly but was able to straighten.
12) I used credit card method to apply paste to cooler sink surface.
13) Yes, pump is installed and works. Radiator fans spin with 450w PSU.
14) n/a
15) none
16) no. but it powers up with 450w
17) no.
18) yes, several times. Tried jumping out the pins with a screwdriver and had no success. The switch works with the 450w PSU.
19) Yes
20) Yes, (ignore warning on PC part picker, I have the b450 version compatible with Zen+ architecture. B450 isnt listed on the website yet, so I have the older b350 version listed).
21) No I haven’t tried cmos. I am not getting power.
22) Unrelated to power issues
23) Yes. Unplugged, replugged, and swapped cables and PSU many times. Have not breadboarded because it works with the 450w.
https://i.imgur.com/JGg7Bhf.jpg backside of mobo
https://i.imgur.com/JMDwoVh.jpg case behind mobo
My problem is simple, but it might be hard for me to explain. I have two PSU’s that I know both to work (they both work in old PC), but only the cheap one works in the new build. By ‘work’ I mean I can get fans/noise/lights/etc. By doesn’t work, I mean nothing, no light, noise or fans. They are both fully modular and I have swapped the PSU’s several times and consistently get the 450w PSU to work and never have got the 750w PSU to work. I need the 750W PSU to work in my new PC because I plan on maximizing CPU overclock and running a 1080TI.
I built a new system and plan on reusing the PSU and GPU from my 2015 build. I have built the 2015 build back up so I have 2 pc’s and am able to independently test and isolate components.
The cheap 450w EVGA PSU works in both PC’s. The nice 750W EPS rated Corsair RM750i works in the old one, but not in the new build. I have tried the new 24pin, 8pin CPU, and VGA cables as well as the original ones from the old PSU.
To reiterate: My new computer MSI motherboard gets power with 450w PSU. The PSU is fully modular, so I unplug everything from the back of the PSU swap and the to the 750w PSU, which does not give power to the mobo when I hit the power switch. I don’t touch anything else, and the cables are all still plugged in the same way to the board, GPU, sata fan hub, CPU 8 pin, etc.
My question is, how could the motherboard possibly see a difference between these two power supplies that I know to both work?
edit 18SEPT2018- Last night was going to attempt to load windows using the 450w PSU, however I couldn't get power (lights, fans, noise), which is just like the other 750w PSU that I want to use. This marks the first time I couldn't get that PSU to work, and I am not sure what changed. I took the parts out of the case to bread board, and I was back to where i was when I made the post - I get power with the 450w unit and not the other one. Now I check the power supplied with the power supply tester. The EVGA 450W unit tests out, see pictures linked below. When I powered up the 750w Corsair psu, I heard a loud arc, a puff of smoke, and the wires were noticeably warm near the woven cable sheath (all events were on the CPU 8 pin cable). But.... nothing else seemed to happen. The power supply tester still gave me results, only notable thing was the 2nd 12v rail was not reading. I spend the rest of the evening reading. This particular power supply is designed to be single rail by default, but configurable to multi-rail. I plan on rebuilding my old 2015 pc with this PSU and logging into corsair link to customize the rail options to make sure all the rails are good. https://i.imgur.com/yhbp8vk.jpg https://i.imgur.com/tbmfaIN.jpg https://i.imgur.com/S2P6KiX.jpg https://i.imgur.com/yjE1TlB.jpg
Edit 19SEPT2018 - I think I found the problem and the source of the inconsistencies and strange behavior. The ATX 24pin both board plug is obviously very standard, however what I did not know is the PSU side of that cable connector plug can be a proprietary pin-out subject to the PSU manufacturer. I said I kept all the cables (fully modular) with the case and only unplugged the PSU side to swap power supplies to troubleshoot problems, which was a no-no. I noticed the 18+10 pin PSU side of the ATX24-pin plug was different between the two manufacturers. I loaded into BIOS last night with all the new parts, so my new rig seems to be okay. The old rig might have some problems, I'll have to spend some time with it.
I suspect this is an issue between my motherboard and PSU, so here are OEM links to them both.
https://www.corsair.com/us/en/Power/Plug-Type/rmi-series-config/p/CP-9020082-NA
https://www.msi.com/Motherboard/B450-GAMING-PRO-CARBON-AC/Overview
New systems that shows the reused parts (Corsair RM750i PSU and GTX 1080Ti)
https://pcpartpicker.com/user/Ulvinator/saved/Dr2xGX
2015 build has the following parts, after I rebuilt it with a new cheap PSU and old GPU.
https://pcpartpicker.com/user/Ulvinator/saved/7K98YJ
I have completed this this and address all issues that would prevent me from getting power (I skipped the steps that might prevent post or boot, but are unrelated to power). Notes below.
http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems
1) I read the manuals
2) The motherboard has an 8 pin CPU plug, and also a separate 4 pin CPUpower2 plug. This 4 pin plug should be unnecessary (at least until its overclocked), but I have tried both PSU both with and without this additional plug.
3) Standoffs are appropriate, pictures of case and back of board attached/included.
4) Yes, I get power with 450w PSU.
5) Yes, many times. New and old cables.
6) Yes, neither stick works, but this wouldn’t prevent power.
7) Yes
8) Yes
9) n/a
10) yes
11) I bent 2 pins slightly but was able to straighten.
12) I used credit card method to apply paste to cooler sink surface.
13) Yes, pump is installed and works. Radiator fans spin with 450w PSU.
14) n/a
15) none
16) no. but it powers up with 450w
17) no.
18) yes, several times. Tried jumping out the pins with a screwdriver and had no success. The switch works with the 450w PSU.
19) Yes
20) Yes, (ignore warning on PC part picker, I have the b450 version compatible with Zen+ architecture. B450 isnt listed on the website yet, so I have the older b350 version listed).
21) No I haven’t tried cmos. I am not getting power.
22) Unrelated to power issues
23) Yes. Unplugged, replugged, and swapped cables and PSU many times. Have not breadboarded because it works with the 450w.
https://i.imgur.com/JGg7Bhf.jpg backside of mobo
https://i.imgur.com/JMDwoVh.jpg case behind mobo
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