Check if the faulty PSU unit is causing issues with other hardware components.
Check if the faulty PSU unit is causing issues with other hardware components.
Hi all, I’m facing some problems with the newly acquired Corsair RM850x SHIFT PSU. From the start, I encountered issues between Q code 19 and code 78, preventing any boot. I attempted to rearrange the RAM sticks (using g.skill tridents), but this resulted in B5s and other memory-related codes appearing. Later, when I reinserted the RAM into the standard 4-drop configuration, I still got stuck at Q code 19 or 78 without a successful boot.
~ Q 78 refers to ACPI module initialization; Q 19 appears to indicate a CPU problem, though I’m not certain what it means exactly.
A few months later, after the original PSU failed (the fractal design), I replaced it with an older PSU and an old NVIDIA GPU from the 400 series for testing. This replacement unit is a budget model: EPS-750W. Details are available here:
https://www.inter-tech.de/3444/EPS-750W_EN.html
This PSU functions normally on Windows (versions 7 and 64), but it clearly won’t support the RTX3070 Ti. It lacks modularity and necessary cables. Now, looking back at the current situation: with this PSU, the system remains stuck at codes 19 or 78 and doesn’t boot. When I removed the RM850x and used the old EPS-750W again, the system started booting correctly.
So, the issue seems to be that the RM850x unit is not working properly with this setup—either faulty or incompatible. All case fans operate, but the CPU fans are absent. I’m using identical cables on both units, though the RM850x PSU has a split 20-pin and a 4-pin connector, while the old PSU has a single 24-pin output. Am I missing something obvious?
Thanks for your time.
Welcome to the forums, newcomer!
EPS-750W
https://www.inter-tech.de/3444/EPS-750W_EN.html
This appears to be a low-quality product. It shouldn't even be considered a power supply unit.
https://www.reddit.com/r/hardware/commen..._exploded/
Could this indicate the RM850x is defective?
There have been several discussions on these platforms suggesting that the Shift series might have been affected by a faulty batch. It might be wise to reach out to your seller and Corsair to initiate an RMA process.
I'm using identical cables for both units, though the ATX 24 pin cable on the RM850x is split into a 20-pin and a 4-pin section, resulting in two different outputs combined into one 24-pin ATX connector.
Are you using cables designed specifically for each PSU? For clarity, consider sharing how your units are connected to the power supply side.
Just a note, you may want to upgrade to a higher wattage PSU if you plan to keep the RTX3070Ti, as the RTX3000 series experienced significant transient load spikes.
use two separate PCI cables or the pc will not start. avoid using one GPU cable. you must connect with two distinct cables to the power supply. skip the extra connector on the PCI cable—only one cable provides 150w. it won’t draw power from the motherboard but only from the PSU. don’t reuse the old PSU; it’s a triple rail design and highly unreliable. its rails are divided into three, not a single strong rail, making it prone to failure.
I suggest opting for the exact cables included with each power supply, unless you're referring to extensions.
Thank you all,
The EPS 750W was only used to verify if the Fractal Design had taken the Mobo og Ram along with it when it failed.
It hadn't, fortunately.
I wasn't able to test the 3070ti with the EPS 750W either. But I could confirm the PCIe lanes remained functional by connecting the old Nvidia GT400 series GPU instead.
The issue lies with the new Corsair RM850x shift – the system won’t boot at all. It freezes on Q code 19 or Q code 78, regardless of whether the 3070ti is in or not.
I made sure to use two different PCIe outputs for the 3070 as well.
It’s puzzling why the system doesn’t even start with this new RM850x model.
All fans are spinning except the CPU fans with the RM850x, and when I use the old EPS-750W power supply, it boots properly.
I’m confused about what might be causing this problem.
It seems extremely difficult to set up the RM850x cables correctly. Either I’m making a connection mistake, or the device is faulty or incompatible with my MBO or RAM. 🤔
It's just that on the RM850x - the 24-pin-ATX-cable - is split - with a 20-pin beginning - and a 4-pin beginning - from two different output - when plugged into the PSU - while ending up in one ATX-24-pin - in the other end - (the one that goes into the mobo) -
Hideous design I might add.
Without bothering you with a long review - just a warning to others who might think about buying an rm850x shift.
Cheap plastic cords - non-sleeved - and the plugs that go into the PSU itself - are much smaller than usual - and the output-ports (I don't know the correct word for them), are so close to each other it's a pain getting your fingertips in between to pull them out without forcing too much - unless one has child size hands.
I won't buy Corsair again that's for sure. Not PSU units at least.
Fractal Design had all kinds of goodies with their unit - sleeved cables, etc.
Oh well. I should've just researched better. I was just too eager to get it running.
I'm still unsure if the unit is faulty though since it lights up the board and all fans (except the CPU fans) are spinning as they should.
Could it really do all that, and then just not feed the CPU enough to finish posting/booting ?