SDCard / FatFS Example Problem (and partial solution)

Question

I'm starting to work on SDCard reading, and was having issues. 
 My problem was that in diskio_blkdev.c, this code: 
 if (err_code == NRF_SUCCESS)
{
 while (m_drives[drv].busy)
 {
 m_drives[drv].config.wait_func();
 }
 
 // right here...
} 
 Where I've got the "right here", m_drives[drv].last_result would always be NRF_BLOCK_DEV_RESULT_IO_ERROR (1), which matched a lot of the other questions. 
 I went through all the other SDCard/FatFS example problems in devzone: 
 
 I set my NRFX_SPIM_MISO_PULL_CFG to NRF_GPIO_PIN_PULLUP (it had previously been pulldown) 
 I verified all my wires (about 8in-long 0.1in hobby connectors) were in solidly 
 I double-checked that all my wires were in the right GPIO pins 
 I double-checked that the actual pins used for the APP_SDCARD_CONFIG macro in main.c matched the pins that the example docs expected 
 I used Windows and quick-formatted my 32gb sandisk SD Card to Fat32 / 4096-byte block size (it was previously Fat32 / unknown) 
 I lowered my APP_SDCARD_FREQ_INIT and APP_SDCARD_FREQ_DATA to 33554432 (thus setting the SPI frequency to 125khz) 
 
 But after all that, it was still failing. Stay tuned for the solution.

arthare · Answer

The solution for me was to power it off the 5V line on the dev board instead of the VDD line like the docs suggested. 
 My multimeter indicated the VDD line was only supplying 2.9V from the dev board, but the example docs suggested it should've had 3.3V 
 However, I'm unsure if this is "correct" - am I going to fry my SD Card? Should 2.9V have been enough?