Dell Inspiron 17R 5737 - slow AMD graphics

Hi,

I've grabbed laptop as per title, and had to install back Windows (due to no HDD).

Windows 10 is fresh, all the drivers are newest from Dell website, all updates from Microsoft are done. The issue is - when I run Furmark to see if everything works - the GPU and vmem seem to work underclocked. Furmark shows 400/300 under full load (GPU in 94%)  accordingly, whether it should be 800/1000 (techpowerup). When idle, GPU-Z shows sometimes 400/150 as I understand this is a lowest possible GPU profile. I'm not convinced this is all about - for example - DDR3 real and effective frequencies, because this simply looks like it worked slow. Furmark's 455 points and 8 FPS in short benchmark indicates it might be 400/300.

Question is - why this laptop runs GPU & vmem so slow ? Temps in Furmark goes upto 58 deg, so I'd say it's pretty good with some place to clock GPU higher.

I didn't install AMD Adrenalin drivers, as they are not supposed to GPU integrated into laptop's motherboard (not as a separate MXM card), it's why I used Dell's one (Catalyst). I've added Furmark to "high performance" profiles, but it won't change anything. Laptop is on AC/DC. BIOS is the newest A12.

Did I miss something ?

Thank you for any clues.