Set target HD as first to boot in BIOS setup, then boot DVD using one-time BIOS BOot Menu key given on first boot screen.
Test your RAM using memtest86 for 5-6 passes, remove 2gb to try install, then swap sticks.
Unplug all other HD's. Did you wipe your HD with zeroes? Run Disk Check
, then test using HD maker's full diag/repair CD scan: SSD / HDD : Optimize for Windows Reinstallation
Do you have the latest BIOS version update? Try setting SATA controller to ACHI, then IDE if necessary.
If you have onboard graphics chip, disable video card to try install. Install driver for card later.
ISO might be confirmed good, but verify the DVD using ImgBurn: load ISO, confirm "Bootable" in text at left, insert DVD, click Verify button. Burn another at 4x if necessary.
Try install from USB flash stick: USB Windows 7 Installation Key Drive - Create
If nothing works, then swap HD into another machine, unplug other HD's to install, remove to problem machine. If Windows 7 starts up it will swap out all drivers, requesting several restarts. If not try booting into Safe mode to change out chipset and video driver. Or boot Windows 7 DVD/Repair CD to run Startup Repair repeatedly.