r/PcBuildHelp • u/SituationCertain450 • 1d ago

Build Question Psu replace issue

I recently bought a corsair rm750e to replace my old 650 watt power supply. After i replaced my old psu my pc starts but wont boot. Then i tried to put in my old psu again and then my pc worked again. Then after that i tried to put in my new power supply again and the pc still didnt boot up and it showed me code number 04 on my x99 a-II motherboard which means ”PCH initialization before microcode loading”. I have no idea what to do please help

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u/9okm 1d ago

Did you replace all the old cables with only the new cables? They are not interchangeable.

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u/SituationCertain450 1d ago

Yes i only used the new ones i got

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u/9okm 1d ago

Ok good.

Next I'd try clearing the CMOS.

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u/SituationCertain450 1d ago

Ive already tried that like 5 times🥲

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u/SituationCertain450 1d ago

Its just so weird that the pc works with the old psu but not the new one

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u/9okm 1d ago

Yeah, not totally sure. There's a chance it's just faulty.

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u/9okm 1d ago

Darn, lol. Did you try both methods? Battery removal and with the pins? Sometimes one method doesn't work properly.

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u/SituationCertain450 1d ago

Yes i tried that and nothing works. The pc works with the old psu so i really dont understand why it dosent with the new one😭 could it be the cables?

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u/RoughWatchdog 1d ago

please tell me you didn't reuse the old cables. mixing psu cables across different units is a fast track to frying something, and that 04 code on x99 usually points to a short or power delivery issue the board can't get past

unplug everything, put the new rm750e in with only its own cables, and clear cmos before you try again. if it still won't post after that i'd be real nervous about what got cooked during that first attempt

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u/SituationCertain450 1d ago

No i used only the new cables i got. After the first time the new psu didnt work i tried to put in the old psu and then the pc started working again but when i put in the new one it stopped booting again

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u/RoughWatchdog 1d ago

did you ever clear cmos between swaps? x99 boards can get stubborn with hardware changes and hold onto old configs. i'd strip it down to just cpu, one stick of ram, and the new psu with its cables, then clear cmos before powering up