You can safely replace the internal microSD cardin theHD7 to increase storage space (up to 32GB cards) and maybe even performance.
Warning: This mod will void your HTC HD7 warranty!
What you need:
One or two plastic opening tools, you can use this.
A T5 Torx screwdriver
One of the following microSD cards:
Sandisk Class 4 8GB microSD – SDSDQ-008G-J35A (used in 8GB version)
Sandisk Class 4 16GB microSD – SDSDQ-016G-J35A (used in 16GB version, tested)
Sandisk Class 2 32GB microSD – SDSDQM-032G-B35 (tested)
First you need to disconnect all cables and turn off your phone by pressing and holding the power button, now remove the top back cover, the battery and your SIM card. The red dots on the bottom back panel with the metal strip indicate two hinges which face towards the bottom of the phone. You need to use the plastic opening tools in the green marked areas in the image linked above and thrust the bottom cover towards the battery area to remove it without damaging it. Now if that’s done, get your screwdriver ready and unscrew all the screws marked with the yellow/green circles. One of them has a tiny warranty sticker on it. If you removed all the screws and put them in a safe place, lift up the cover, you can do that using the kickstand, don’t worry, even though you removed two screws there, it’s not loose.
Now, if you’ve done that, peel off the gray cloth tape strip covering the microSD card slot and push the SD card a little into the slot to remove it using the spring load. Now insert your new SD card, reassemble the phone, hold down both volume buttons and power it on, keep the volume buttons pressed until you see blue text on gray background, then release both volume buttons and press volume down to reset your phone to factory settings. Enjoy your capacity upgrade.
If you would like to be able to use your old SD card in another phone or your computer, you will need to format it using a device with secure digital password protection support. You don’t need to know the password for that. Most Symbian devices can do this, if you don’t have one, try to ask the nice person in your local mobile phone store to lend you one for one or two minutes.
After the mod you can see that the 32GB Class 2 card is actually faster than the one that came with the HD7.