Heres an break down of what you'll need to do.
You will first need to extract your electrum wallets hash and determine which salt type it is. This is typically done by using john the ripper. Once you have your hash you will need to figure out which mode it is on hashcat.
There is 3 modes for electrum, correspond to the example hashes to determine which yours fits into.
https://hashcat.net/wiki/doku.php?id=example_hashes
See mode 16600 (salt 1-3), mode 21700 (salt 4) & mode 21800 (salt 5).
Here is an example of a rig with 4x 3090's using mode 16600 for number crunching.
Code:
CUDA API (CUDA 11.5)
====================
* Device #1: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #2: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #3: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #4: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
OpenCL API (OpenCL 3.0 CUDA 11.5.125) - Platform #1 [NVIDIA Corporation]
========================================================================
* Device #5: NVIDIA GeForce RTX 3090, skipped
* Device #6: NVIDIA GeForce RTX 3090, skipped
* Device #7: NVIDIA GeForce RTX 3090, skipped
* Device #8: NVIDIA GeForce RTX 3090, skipped
OpenCL API (OpenCL 3.0 WINDOWS) - Platform #2 [Intel(R) Corporation]
====================================================================
* Device #9: 11th Gen Intel(R) Core(TM) i5-11400 @ 2.60GHz, skipped
Benchmark relevant options:
===========================
* --optimized-kernel-enable
---------------------------------------------------
* Hash-Mode 16600 (Electrum Wallet (Salt-Type 1-3))
---------------------------------------------------
Speed.#1.........: 1620.7 MH/s (52.37ms) @ Accel:8 Loops:512 Thr:256 Vec:1
Speed.#2.........: 1651.0 MH/s (51.37ms) @ Accel:8 Loops:512 Thr:256 Vec:1
Speed.#3.........: 1625.0 MH/s (52.22ms) @ Accel:8 Loops:512 Thr:256 Vec:1
Speed.#4.........: 1655.2 MH/s (51.24ms) @ Accel:8 Loops:512 Thr:256 Vec:1
Speed.#*.........: 6552.0 MH/s
Started: Wed Mar 16 20:58:11 2022
Stopped: Wed Mar 16 20:58:32 2022
Here is mode 21700
Code:
CUDA API (CUDA 11.5)
====================
* Device #1: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #2: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #3: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #4: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
OpenCL API (OpenCL 3.0 CUDA 11.5.125) - Platform #1 [NVIDIA Corporation]
========================================================================
* Device #5: NVIDIA GeForce RTX 3090, skipped
* Device #6: NVIDIA GeForce RTX 3090, skipped
* Device #7: NVIDIA GeForce RTX 3090, skipped
* Device #8: NVIDIA GeForce RTX 3090, skipped
OpenCL API (OpenCL 3.0 WINDOWS) - Platform #2 [Intel(R) Corporation]
====================================================================
* Device #9: 11th Gen Intel(R) Core(TM) i5-11400 @ 2.60GHz, skipped
Benchmark relevant options:
===========================
* --optimized-kernel-enable
--------------------------------------------------------------------
* Hash-Mode 21700 (Electrum Wallet (Salt-Type 4)) [Iterations: 1023]
--------------------------------------------------------------------
Speed.#1.........: 677.5 kH/s (73.95ms) @ Accel:32 Loops:63 Thr:512 Vec:1
Speed.#2.........: 697.5 kH/s (71.87ms) @ Accel:32 Loops:63 Thr:512 Vec:1
Speed.#3.........: 695.5 kH/s (72.40ms) @ Accel:32 Loops:63 Thr:512 Vec:1
Speed.#4.........: 696.8 kH/s (72.00ms) @ Accel:32 Loops:63 Thr:512 Vec:1
Speed.#*.........: 2767.3 kH/s
Started: Wed Mar 16 20:59:25 2022
Stopped: Wed Mar 16 20:59:50 2022
Depending on the Iteration count your speeds could be significant different than expected. If you have a general idea of what your password could be using a base wordlist and applying rules would be the best option for attempting to crack your password. I would start by doing this
prior to renting a system and wasting your credits. Familiarize yourself with how hashcat works on your current computer and the recommended drivers required for it to operate. Check out the wiki for several attack modes and variations you can apply.