dual channel DDR4 not booting

[superkay1993]

newly built PC, motherboard is ASRock z370 Pro4, with Corsair DDR4 Vengeance LPX Red, PC4-19200 (2400), Non-ECC Unbuffered, CAS 14-16-16-31, XMP 2.0, 1.2V

x2 4gb single sticks, not a kit

the mobo states to put them in B2 and A2 how ever anything in A1 or A2 wont allow the PC to boot,
either stick works in B1 or B2, but neither work in any configuration that involves A1 or A2

any ideas? as for now im running in single channel as opposed to dual channel

sure this has nothing to do with the sticks not being part of a kit as they are the exact same just individual and hte fact that its slots A1 and A2 that are suspect

any ideas or guidance?

 

[MeanMachine41]

Never a good idea to mix RAM even with the same exact specs. Kits are binned by the factory due to slight variations in Latency during manufacture. There is no guarantee when mixing RAM and manufacturers warn you of this. Sure sometimes your lucky and with some Bios changes to Primary Timings and voltage, they can work together.
Unless you have dead RAM slots (unlightly) your issue is a mismatch and to help understand this issue go here: https://rog.asus.com/forum/showthread.php?57038-Don%92t-combine-memory-kits!-The-meat-and-potatoes-overview.
Best is to select a single kit that are listed on the MB QVL, the size and frequency you require,that have been tested.

 

[superkay1993]

Never a good idea to mix RAM even with the same exact specs. Kits are binned by the factory due to slight variations in Latency during manufacture. There is no guarantee when mixing RAM and manufacturers warn you of this. Sure sometimes your lucky and with some Bios changes to Primary Timings and voltage, they can work together.
Unless you have dead RAM slots (unlightly) your issue is a mismatch and to help understand this issue go here: https://rog.asus.com/forum/showthread.php?57038-Don%92t-combine-memory-kits!-The-meat-and-potatoes-overview.
Best is to select a single kit that are listed on the MB QVL, the size and frequency you require,that have been tested.

but surely its not a ram issue as both sticks are identical and they should work in slots A1 or A2 together or on their own but the PC wont boot so im suspecting the A2 and A1 slots on the motherboard

 

[ElectrO_90]

I had this exact same problem on my Z87 Asrock motherboard.
I could never figure it out so I had to put one in A1 and one in B1 - it would otherwise not boot with both in A1/2

I have a Z97 now and they work in A1/A2.... so no idea what the problem was, unless motherboard was faulty, but it didn't ever work from the get-go.

 

[MeanMachine41]

Here is the memory QVL for Z370 Pro4: https://www.asrock.com/MB/Intel/Z370%20Pro4/index.asp#Memory

Although it could be dead RAM slot, Best is to first try a different RAM kit from the QVL. Just ensure you can return them if they don't work.?

I recommend a 16GB (2x8) single kit that your CPU will support and have been tested.
If not sure which kit to get then I will recommend a 16GB kit that are known to work, just list the CPU.?

 

[ElectrO_90]

If you don't use the XMP, does it work?
Do you see both RAM sticks in BIOS before XMP is ready to boot up?