Buying Advice - M.2 on a motherboard with only 2x PCI-E 2.0 lanes (Asus Z97i Plus)

[carbide]

Hi!

With black Friday approaching and running out of storage I'm thinking of adding another drive.

Current:

850 Pro 1tb boot drive
MX300 750gb storage
WD 3tb HDD storage

So that's 3 of 4 SATA used. I'm thinking of getting an M.2 drive and using that as the boot disk, giving me the 1tb 850 pro as storage.

Concerns: I only have 2x pcie 2.0 lanes available, so ~1gb/s bandwidth. I see read that, real world, only 'read' benchmarks get around 2gb/s and write ~1.5gb/s.

If I buy a good quality m.2 drive (thinking ADATA 1tb gammix or sx8200) will it be a waste? I'm thinking it will be an investment, especially when I move to x390 or up in the next year or so. However, in the sale, I might be able to grab a 1tb MX500 SATA for, maybe £100-£120, and by the time I'd realise the full performance of an M.2 drive, they'll (hopefully!) be about that price anyway.

I'm a bit torn as to which way to go. Thoughts appreciated...

 

[vapour]

https://www.asus.com/Motherboards/Z97IPLUS/\

it says M2 is max 10Gb/s ~ 1.25GB/s, I will just get a normal M2 sata SSD like Crucial MX500

 

[Rogue Leader]

https://www.asus.com/Motherboards/Z97IPLUS/\

it says M2 is max 10Gb/s ~ 1.25GB/s, I will just get a normal M2 sata SSD like Crucial MX500

Unless you need the form factor M.2 SATA SSDs are a waste of money, they are no faster than a normal 2.5" SATA drive.

As for the drive though I agree, waste of money, that thing Is $340 and you're not going to get $340 worth of performance out of it with only an x2 slot that doesn't support NVMe. IMO if you need more drive space normal SSDs are SUPER cheap right now. Then when you actually can use the performance, NVMe SSDs will likely be cheaper.

 

[carbide]

looking at the best answer from this thread: http://www.tomshardware.co.uk/answers/id-2316705/pcie-slot-utilization.html

it would seem pcie 3.0 is 985mb per lane, pcie 2.0 is 500mb per lane.

as per the link to the other thread, I think I'd have 1000 gb/s transfer speeds, 50% of what an nvme m.2 pcie drive read speed is capable of, but for all other throughput tests, might not be that much of a bottleneck.

taken from user benchmark:

sequential
Read 2,111
Write 1,409
Mixed 1,198
SusWrite 1,421
343% 1,535 MB/s


Random 4k
4K Read 58.8
4K Write 137
4K Mixed 79.9
264% 92 MB/s


Deep queue 4k
549 DQ Read 1,030 1,301
234 DQ Write 829 1,106
321 DQ Mixed 910 1,174
686% 923 MB/s


it only seems like sustained sequential read/write saturates 2 lanes being over 1000mb/s. So, the question is, day to day, will I still get the majority of the benefit? I assume apart from big compression/decompression moving of big zipped datasets, the rest of the workloads will have the same performance improvement as if I had 4x lanes available?

 

[Rogue Leader]

Day to day unless you're doing monster data transfers you won't notice a performance difference. Your games aren't going to load faster (at least nothing you can ever perceive). Hence why I said you won't see "$340" worth of performance out of it, and when you can get a regular SSD for 1/3 of that price its a waste. Better to save the excess for your future upgrade plans.

 

[carbide]

Thanks Rogue, everything you say makes sense. As always, you always want faster, but in this situation, I just don't think paying 1.5x more will net any tangible benefits. and by the time it would, it'll probably only cost half the price, and I'll have eaten well into it's warrantied lifespan.

Thanks for the advice!

 

[Rogue Leader]

Thanks Rogue, everything you say makes sense. As always, you always want faster, but in this situation, I just don't think paying 1.5x more will net any tangible benefits. and by the time it would, it'll probably only cost half the price, and I'll have eaten well into it's warrantied lifespan.

Thanks for the advice!

Any time glad to help.