HDD Write Speed Extremely Slow

[SpicyTM]

So a couple months ago i started a download for a game on steam but when i was checking it, it would download at 400kb for like 10 secs and say busy writing to disk for a whole minute
i have 50DL and 4UP and steam usually downloads at a steady 6Mbps

I checked my main HDD write speed and it was around 100Mb then i checked my other HDD and the write speed was at a really slow 200Kb
I used a 3rd party program to check its status crystaldiskmark or info and both HDD's were fine
so i used S.M.A.R.T from CMD and it also said both HDD's were just fine so i really dont know whats going on
I am getting a new 1TB real soon and by that im doing a whole new build and i wouls like to turn my current PC into a home PC for my family but thats not gonna work out to well with a failing HDD that isnt being detected or something.
So does anyone know some tricks i could try to fix this or is it done for?

Oh and it couldnt have been heat or anything since my HDD's are literally always at body temperature level
31C - 36C
The HDD is also about 7 years old so it could just be dying but i want to know why its problems arent being detected by SMART or any programs

 

[ignatzatsonic]

Download the disk utility from the hard drive manufacturer's web site.

It probably has a couple of tests. Run the quick one. If it passes that, run the longer one.

SMART isn't entirely reliable. Drives can go bad at any time with no warning.

But you may have healthy drives that are being affected by something else---malware for instance.