No, a large number of GPUs in parallel would not be equivalent to a quantum computer for solving DES or AES decryption.
Quantum computers, with their unique computational properties derived from quantum mechanics, have the potential to solve certain mathematical problems, including factoring large numbers, which are used in the cryptographic algorithms like RSA that underlie systems such as DES and AES. Quantum computers can exploit quantum algorithms, such as Shor's algorithm, to efficiently factor large numbers and break the security of these encryption schemes.
On the other hand, GPUs (Graphics Processing Units) are powerful processors primarily designed for parallel processing of graphical computations. While GPUs can be used for general-purpose computing (GPGPU) and perform certain types of computations faster than traditional CPUs, they are not designed specifically for quantum computing tasks. GPUs excel at tasks that can be parallelized, such as graphics rendering, scientific simulations, or machine learning algorithms, but they do not possess the inherent quantum properties necessary for solving problems like factoring large numbers efficiently.
In summary, while GPUs can provide significant computational power for certain types of calculations, they are fundamentally different from quantum computers in terms of their underlying principles and capabilities. Quantum computers offer the potential to break certain encryption algorithms like DES and AES efficiently, while parallel processing with GPUs does not provide an equivalent solution for these specific cryptographic tasks.