You can’t do that.
I know it might be tempting to open up that DIRECTV receiver and put in a bigger hard drive, swap out the power supply, or otherwise tinker with it, but you can’t do that (in most cases.)
If you’re using DIRECTV at home, your receiver is leased. It isn’t your property, and unlike an apartment or car that you lease, you can’t even make minor changes. You have to keep it exactly as is. This may seem like a real drag if you’re trying to do something like deal with a noisy fan or loud hard drive, but it’s what you signed up for.
If you’re a commercial customer, in most cases you’ve bought the hardware and you own it. Unfortunately this doesn’t always mean you can do what you want. You may be free to make modifications but then the receiver may not work. Even something fairly benign may make this fairly complex computer think it’s been tampered with, and tampering is something DIRECTV simply doesn’t want.
Blame the content protection scheme built into every program on DIRECTV. It’s designed to make the TV networks comfortable by making it almost impossible for you to get a perfect, unencrypted high-definition copy of the programs you receive. If you could do that, you would be able to rebroadcast them illegally and that would undercut the whole system where DIRECTV pays the networks and the networks get rich.
If you do want to make a change to your DIRECTV system — for example to make it work better on your boat, or to add more hard drive space — you’re much better off making that change using something external instead of digging into the guts of your receiver.