ASUS Zenbook Prime SSD performance comparison: Sandisk vs ADATA


ASUS made quite a splash with the new Zenbook Prime UX31A and UX21A. Although there is a lot to like, there are a few customers that feel a bit cheated by an underperforming SSD that is included.

The problem is that the Zenbook Prime ships with one of two very different SSDs which have the same capacity but dramatic differences in performance.  When you open the box you will either discover a fast ADATA XM11, or incredibly slow Sandisk U100 SSD. The model numbers are exactly the same so until you have the box in your possession and look at the sticker, there is no way to know what you are getting.

ASUS sells from a variety of online retailers so seeing the box before shipping is impossible. To make matters even worse the SSD has a non-standard connector so if you happen to get stuck with the Sandisk (like I did),  there is nothing you can do about it. ASUS customer service said there was nothing they could do, and said it would void my warrenty if I attempted to swap it out. Not cool ASUS, not cool.

Normally this type of thing wouldn’t be an issue as suppliers routinely do this all the time, but in this instance, the performance is not in the same ballpark.

Below are the benchmarks of the Sandisk U100 compared to the ADATA XM11 as well as a couple others to provide some perspective. Both drives tested are the 256GB SSD models, but from what I have seen the 128GB models have similar performance profiles.

AS SSD Benchmark – Sandisk vs ADATA

Large sequencial writes are the only test that looks respectable and the only winning metric for the Sandisk.  While the sequential reads, 4K random reads, and 4K random writes are terrible. Access times on the Sandisk are twice that as of the ADATA.

ATTO Benchmark – Sandisk vs ADATA

In this benchmark we see similar results as the last. There are slow writes across the board for the Sandisk. The ADATA appears to be in another class altogether for the small reads and writes. Note the range differences on the X axis of both tests.

Crystal Disk Benchmark – Sandisk vs ADATA

This benchmark shows the results with the most clarity. In some cases the ADATA is an order of magnitude faster than the Sandisk SSD.

For a better overall comparison I have included the results of the Sandisk vs a traditional mechanical hard drive as well as the new Samsung 840 Pro series SSD which is at the top of its class as far as SATA3 SSDs are concerned.

Crystal Disk Benchmark – Sandisk vs Traditional HDD

The Sandisk look marginally better compared to a traditional rotational hard disk drive.

Crystal Disk Benchmark – Sandisk vs Samsung 840 Pro SSD

When you look at the results of the comparison to the new Samsung 840 you get a sense how bad the Sandisk drive really is.

Bottom Line:

The Sandisk U100 is truely one of the worst SSDs that you can get these days. Although still better than a traditional HDD, when compared to the ADATA XM11 or  the Samsung 840 Pro you can see how poorly it performs as a SSD.

This is unfortunate as ASUS makes it nearly impossible for a customer to determine which model they are getting before purchase. And if they get stuck with the Sandisk, there is no course of action to replace or swap out the drives. The Zenbook Prime is a very nice laptop but hopefully ASUS will get their act together and fix this issue ASAP.

You can also check out my full review of the Zenbook Prime UX31A.