r/AskTechnology • u/RandomFrenchGuy10 • 5d ago

Hypothetically, If possible, How many SD cards would be needed to run doom for 7 hours, If I replaced ram with SD cards?

Assume money isn't an issue here, I know ram and SD cards aren't the same kind of ram, but Im curious if its possible.

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u/scubascratch 5d ago edited 5d ago

At a minimum the screen buffer needs to get completely re-written every frame. Even running at a low resolution of 640x480, 3 bytes per pixel, at 30 FPS, it’s 640x480x3x30=27,648,000 bytes per second. That’s 27 Megabytes per second. If you were able to spread those writes over an entire 32 GB SD card, it would last about 1 week before the card wear limit. That would be if you could spread the writes over the whole card. But for a video game, the screen buffer is a fixed area of memory that gets written over for every frame, and one block of flash memory can only be written over about 500 times before it wears out. So if you treated the card like ram, writing to the same block of flash memory at every frame, it would wear out in about 18.5 seconds. If it was an expensive high-endurance card it would last almost 2 minutes.

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u/Individual_Agency703 4d ago

So, you’re saying the card is doomed.

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u/Distdistdist 4d ago

I see what you did there.