So.
I'm facing a really really weird problem.
My friends brings me his New 3DS XL out of box. Fw 9.6
I downgraded. Format emuNAND and setup Luma3DS 5.5. Menuhax
Injected fbi 2.6. All ok.

Everything fine. But when i tried to install sysupdater to update offline to 11.0 its toke a long time to start installing and stays at 0Mib

But after some time installed.
I updated to 11.0 offline mode with sysupdater.

Well the problem its.

Anything i tried to install its toke long time to start installing. And its slow. Very slow.

Its a 64Gb microsd SDXC 48MBS

When copying game was fast about 15mb/s. I tried a lot of games. Anything even small ones are slow.

Well i have my own new 3ds and the same microsd. Its big difference of speedy with same games.

Ok.

So i decided to start from beginning. Format emuNAND again but wait. New 3ds just freeze and cant format emuNAND anymore.

So i got microsd into my notebook format it and exclude emunand partition but still can't create emunand anymore.

So i have a great idea of backup my own new 3ds xl microsd. And use with his new 3ds. The same problem occurs. Now i cant even create emuNAND with my own card too. Even into my own new 3ds.

I toke another microsd and format emuNAND into my new 3ds and works well everything back to normal.


But now i have 2 microsd that was working great not accepting format emuNAND.

I dont know whats going wrong.

Maybe his new 3ds are corrupting the microsd?

Before everyone says.

Its a original microsd sdxc 64gb from sandisk. Its no fake. If it was fake should not even working with my new 3ds with 40gib games installed.

Sorry for long history. But im really upset with this.

 

Even though you say it's not a fake it still could be. It could be a 16GB in disguise and make to seem like a 64GB. From the information you gave me thats the best response I could give.

Sent from my Samsung Galaxy S7

 

Sometimes the packaging is identical between the real cards and the fakes. And sometimes, fake cards have the advertised capacity but are using bad quality memory, which can fail within a short amount of time.
You might just have had bad luck with the card though. Sometimes legit memory cards can fail within a short amount of time, I had a legit Transcend card fail on me within 6 months after buying it.
You should try to format emuNAND using emuNAND9's "Complete emuNAND Setup" (run it from sysNAND homebrew launcher): https://github.com/d0k3/EmuNAND9Tool/releases
emuNAND9 will format your card with 64K cluster size, so it should maximize the speed of the card.
If that fails, or you continue having problems after that, try scanning the card with h2testw: http://www.heise.de/download/product/h2testw-50539/download

 

I have a silicon power micro SD that simply didn't work on my n3DS. Works fine in my computer or my cell phone but did not work on the 3DS at all.

Sent from my Samsung Galaxy S7

 

Corrupted/faulty or incompatible SD Card.
Try with another and see for yourself.

 

Well.
I did a lot of test. Like i said none of my Microsd are fake. All original.
I tried emunand9 and did a emunand format and setup all overagain i even format NEW 3DS and did a fresh start.

Well the 2 microsd keeps being slow to install. But understand that i test it computer and got a good transfer 45mbs for Reading and 15/17mbs for write.
I even got Agent of Shield series in 1080P about 48Gb, and all works verywell. All episodios.

OK!!
I did another test. I setup Luma3DS with a 32GB microsd. For beggining everything was installing very well and fast. But after a time become slow again.

I change the plans and setup A9LH ( ARM9loaderhax ). Everything was fine. It's installed now.

I formated my microsd 64GB, remove emunand partition and now it's all clean.
But keeps slow when installing. I even installed last FBI to tried.


BUT WHEN I SAY slow, it's really really really slow. It's about 0,25Mib each 1,5 seconds.
My old3ds install about 1,5Mib each second. And my New 3DS install about 2,5Mib per second.

But when its start installing it's fast, after a time get slow. Well I dont know what to do!!

 

A 64gb that runs at 15mb/s write and 48mb/s read speed? That's very slow... even Nintendo/s included cards are faster.
Mine is a 80mb/s read speed and that was the worst 64gb option out there. I haven't heard of a card like this.