In most cases, HDD would make a clicking type sound, Fans give off a "whirring" sound.
In many cases, S.M.A.R.T. HDD checking tools can read the drive to be good but still end up failing, so best to backup data as said previously.
If it really is more like a whirring sound, you may be able to notice your fans spinning faster by placing your had over the exhaust vents and "feeling" the air exhaust faster. If you motherboard has sensors to monitor fan speed/temperature, you can use a tool like
SpeedFan (simple) or
HWMonitor (more detailed) to see if it really is just the fan spinning faster during intensive tasks such as aforementioned AutoCAD/Gaming heating up your hardware and needing to increase fan speeds.
- These are temperature/fan speed monitoring tools and the latter extends to voltages/more details e.t.c.
The whirring could just mean
(a) you need to clear out dust
(b) fans are failing and need to be replaced - this could be the cpu/gpu fan or just the exhaust fan
Either way,
best to backup your data whether it's the HDD or the fans and;
(a) contact the place you bought it from
if still under warranty/guarantee period, for them to look at it
(b) take it to an IT Repair Desk/Service for them to check it out
(c) find guides online and try clean out dust yourself (Canned air-dusters may help but rarely help when the issue is this bad)
(d) replace the fans and/or HDD
If you do go for a DIY approach;
Most laptops are very similar in the way they are disassembled/reassembled, you may not get the exact model with the exact screw placements but they'll be good enough to follow and apply to your laptop. Find a video online such as
"Linked Here" (random clear example of similar Asus model) and follow it as a template/guide on how to dismantle to get to the parts (HDD/Fans) - and remember to replace thermal paste