Lag spikes during gaming after having new PC for two days

So basically I've bought a new PC purposefully for gaming, I didn't get top spec components which might be one of the reasons why, but just after two days I seem to get lag spikes in game nearly every 5 seconds which is frustrating and I can't seem to figure out why after a few hours of research. I have only downloaded 2 games so far which are CSGO and PUBG (downloaded on SSD), in which CSGO was running fine within the first day, the second however was when lag spikes started to occur. My knowledge isn't the greatest with PC's but I can totally understand from other people's perspective.

I've started to notice that the lag spikes started during a config custom map in CSGO, is there any chance this could've changed things it shouldn't have?

I use CAM to monitor my PC and also noticed that the GPU temp increases drastically whenever a game is opened to about 70C+, and the load maxes out and drops whenever a lag spike would happen.
I ran an userbenchmark also to confirm it was the GPU and it mentioned it was performing below expectations.. Is there just something wrong with the GPU?

I am running with:

Processor (CPU)
Intel® Core™ i7 Six Core Processor i7-8700 (3.2GHz) 12MB Cache
Motherboard
ASUS® H310M-A: Micro-ATX, DDR4, LGA1151, USB 3.1, SATA 6GBs
Memory (RAM)
16GB Corsair VENGEANCE DDR4 2400MHz (2 x 8GB)
Graphics Card
3GB NVIDIA GEFORCE GTX 1060 - DVI, HDMI, 3 x DP
1st Hard Disk
2TB SEAGATE BARRACUDA SATA-III 3.5" HDD, 6GB/s, 7200RPM, 64MB CACHE
1st M.2 SSD Drive
250GB SAMSUNG 970 EVO M.2, PCIe NVMe (up to 3400MB/R, 1500MB/W)

Any help is greatly appreciated, thank you

We need to clear some things up
- Are we talking about actual lag, or about framerate drops
- we need to use a proper benchmark
- if things were fine on day 1 but not fine on day 2, what happened in between?

I ran an userbenchmark also to confirm it was the GPU and it mentioned it was performing below expectations.. Is there just something wrong with the GPU?

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Userbenchmark is total garbage. Avoid, avoid, avoid.

I'm not saying that there isn't a problem with your GPU. But if there is, userbenchmark is only right in the same way that a broken clock is right twice a day. You will want to run a more robust benchmark.

Use something like Firestrike: https://benchmarks.ul.com/3dmark (you can download it via steam as well as via that website) and post a link to your score.

I use CAM to monitor my PC and also noticed that the GPU temp increases drastically whenever a game is opened to about 70C+

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70 degrees or more is entirely normal for gaming load.

When you say "Lag" what are we actually talking about here? Are we talking about internet lag where you click and it takes ages for that to happen in game / where people run on the spot for ages and then suddenly 5 seconds of gameplay happen all at once - or are we talking about framerate drops where the game 'stutters'?

Are the games installed on the SSD or the HDD?

Have there been any Windows updates since you got the PC home?
https://winaero.com/blog/how-to-see-update-history-in-windows-10/

- side note - this won't be what is causing your performance drops, but that motherboard only has PCIe 2.0 x4 for the M.2 slot, not PCIe 3.0, and so it will bottleneck the SSD a bit. Again, this is not what is causing your problems, but it's something to be aware of.

Are we talking about actual lag, or about framerate drops

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Frame rate drops that would occur every 5 seconds from for eg 150fps down to 30fps

if things were fine on day 1 but not fine on day 2, what happened in between?

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Nothing significant, I've downloaded CAM to monitor my PC..
I've cut and pasted some documents from my previous PC to my new from a USB stick into my HDD
(will post more after I remember)

Are the games installed on the SSD or the HDD?

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They are installed onto my SSD, one thing is though the first partition is the boot drive which I've purposely left for that but accidentally to change downloads to the other partition

I will run benchmarks and install updates and keep posted.

and install updates and keep posted.

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So my question here is whether there have already been updates in case the updates are what have triggered the problem. Windows 10 will generally perform updates without telling you that it's doing them.