Memory Usage counter resets above 4GB - R9 390

[Failquail]

Apologies if this has been reported before, couldn't find anything via a search

I often run GPU-Z on my second monitor for monitoring, when playing subnautica on the highest graphical settings the memory usage counter reads fine until roughly ~4300MB out of the 8GB VRAM usage then acts oddly afterwards, dropping suddenly to ~500MB.
Same game on the recommended preset displays fine, but that only uses ~3GB RAM max...

I don't know if it is just this game or not, as this is the first game i've used that actually has used more than 4GB of VRAM. I can supply more details/logs if required.

 

[W1zzard]

You are on the latest AMD driver I assume?

 

[Failquail]

Pretty much (Crimson 16.1.1 beta driver, but i just looked and i noticed there's a 16.2.1 version available now)

Want me to try that or revert to the non-beta version?

 

[W1zzard]

nah 16.1.1 should be ok, i'll try to replicate

 

[Failquail]

Small update:

Just noticed the same behaviour in XCom2. The game doesn't often go much over 4GB, but if it does go over 4.2-4.3GB the counter drops to ~300MB.
This is with the latest driver (16.3.1)

 

[little cat]

Does something happen after memory usage drops . i mean drop of the FPS , freezing ? It might be a kind of "garbage collection" action or even data comressing . Does it rise after such a drop !?

 

[Failquail]

Nope, exactly the same performance. Also if the memory usage drops a bit (say loading a level in XCOM) it'll jump back up to the correct readings if lower than ~4300MB.

My guess is when the value drops to say 500MB after getting past 4.3GB the card is actually using 4500MB RAM yet GPU-Z can't handle a number that large so the 4 gets knocked-off.