GTX 1660 not recognized using 515 driver

I manage several machines with different Nvidia GPUs that all share the same setup on Ubuntu 20.04 LTS. I have been running the 460 drivers without issue for a while, but recently I got a new machine with the A2000 GPU which was running very slow. Updating that machine to the 515 driver solved that issue, so I decided to upgrade all machines.

It worked fine for A2000, Quadro P2200 and GTX 1050 Ti, but my machines with GTX 1660 (SUPER and Ti) cannot recognize the card (X session cannot start, but ssh still works) after updating the driver, with the error below. I have tried on 3 different 1660 so far, all have the same issue. Downgrading back to 460 makes the system run fine again. Is it that GTX 1660 series does not support the latest 515 driver, or is there something else happening here? hangs forever and does not generate any useful output (same with nvidia-smi command so I assume it hangs trying to get information about the GPU), but please let me know if I can get any other useful debugging information.

kernel: NVRM: GPU 0000:01:00.0: RmInitAdapter failed! (0x26:0x56:1440)
kernel: BUG: unable to handle page fault for address: 0000000000002eb4
kernel: #PF: supervisor read access in kernel mode
kernel: #PF: error_code(0x0000) - not-present page
kernel: PGD 0 P4D 0 
kernel: Oops: 0000 [#1] SMP PTI
kernel: CPU: 11 PID: 842 Comm: nv_queue Tainted: P           OE     5.4.0-54-generic #60-Ubuntu
kernel: Hardware name: Neousys Technology Inc. Nuvo-7000 Series/NVS-7000, BIOS Build191203 12/03/2019
kernel: RIP: 0010:_nv010260rm+0x38/0xc0 [nvidia]
kernel: NVRM: GPU 0000:01:00.0: rm_init_adapter failed, device minor number 0
kernel: Code: 59 07 02 48 8b bb 68 01 00 00 e8 d3 79 4e 00 85 c0 74 0f 48 83 c4 08 5b 41 5c c3 0f 1f 80 00>
kernel: RSP: 0018:ffffa4bcc0dfbdc0 EFLAGS: 00010246
kernel: RAX: 0000000000000000 RBX: ffff99594daa0c08 RCX: 0000000000000000
kernel: RDX: ffffa4bcc0dfbdec RSI: 0000000000000000 RDI: 0000000000000000
kernel: RBP: ffff995951ff6000 R08: ffffc4bcbfcce850 R09: ffffa4bcc0dfbe68
kernel: R10: ffff99594f21e680 R11: 0000000000000001 R12: 0000000000000000
kernel: R13: ffffa4bcc0dfbec0 R14: ffff99595750b9f8 R15: ffff99594f21e680
kernel: FS:  0000000000000000(0000) GS:ffff99595bac0000(0000) knlGS:0000000000000000
kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 0000000000002eb4 CR3: 000000013180a003 CR4: 00000000003606e0
kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
kernel: Call Trace:
kernel:  ? rm_execute_work_item+0x108/0x120 [nvidia]
kernel:  ? schedule_timeout+0x10e/0x160
kernel:  ? os_execute_work_item+0x4c/0x70 [nvidia]
kernel:  ? _main_loop+0x8c/0x140 [nvidia]
kernel:  ? kthread+0x104/0x140
kernel:  ? _raw_q_schedule+0x70/0x70 [nvidia]
kernel:  ? kthread_park+0x90/0x90
kernel:  ? ret_from_fork+0x35/0x40