- In one coder's tests, two AMD chips never gave a 0 when asked for a number from 0 to 65,535.
- An Intel chip running the same test gave zeros just fine.
- A reader's billion-try test on another AMD chip found no usable 0 in that range either.
- Other testers saw it on two older AMD chips, but the newer ones they tried gave zeros.
Some PC chips have a part that makes random numbers, and computers use them as a starting point for the secret keys that keep data safe. Jessé, a programmer in Brazil, asked the one in an AMD Ryzen 7 chip for random numbers from 0 to 65,535. It never gave back a 0, and neither did a second AMD machine. An Intel chip running the same test did. That's odd for a part whose whole job is being random. Ask the same chip for a bigger number and zeros show up, which is the workaround Jessé posted.
Flat assembler forum zero thread
A reader on Hacker News asked an AMD chip for a billion of these numbers. Each answer comes with a yes or no saying whether it worked, and a failed try is supposed to hand back 0. Not one 0 came with a yes. The test logged 15,312 failed tries, all returning 0, close to how many zeros a fair chip would give. That reader suspects the chip does make zeros but wrongly marks them as failures, though the numbers can't prove it.
Hacker News reader test results
Jessé reported it to AMD in May and says the first reply seemed to misread the results. By May 23, Jessé said AMD had passed the case up inside the company but hadn't sent anything more. The thread then went quiet until September 19, and Hacker News found it this week.
The Hacker News post drew more than 200 comments, and more testers joined the forum thread. One tried an older Ryzen 5 1600, which did the same thing, and a newer Ryzen 9 9950X3D, which gave usable zeros. That 9950X3D did show a different random number problem, one AMD has already published a fix for. Another tester got zeros from an AMD server chip, and a third saw the same thing on an older Ryzen laptop chip.
Forum tests on other AMD chips, AMD notice on the newer chip bug
Some Hacker News readers expect little harm, because computers can mix these numbers with other random sources instead of using them directly. None of the reports include an explanation from AMD for the missing zeros.
