Clevo P750ZM: GTX 980M Overclocking Investigated

GTX 980M Overclocking: Do the Time Warp

With the overclocking results in hand, it’s not too difficult to see why people would be upset with NVIDIA locking out overclocking on mobile GPUs. Using the Clevo P750ZM from Eurocom (aka the Eurocom P5 Pro), we were able to easily increase clock speeds on the GPU by more than 10%, and a 20% boost only required the use of an unlocked VBIOS. If NVIDIA follows their usual pattern, the overclocked GTX 980M is likely going to be faster than the next halo mobile GPU from NVIDIA, whenever that shows up (probably in the fall).

Hefty, hefty, hefty...

With those results in hand, NVIDIA’s decision to lock down mobile overclocking might seem like a way to prevent users from getting a free performance boost, but there’s more going on. The biggest concern is that we’re using what is arguably one of the best platforms for GTX 980M overclocking in this article, and while the results are great I wouldn’t count on all notebooks using GTX 980M being able to achieve similar clock speeds.

Case in point: the Gigabyte P35W v3 discussed on the previous page. Depending on the game and settings, the CPU can be a bigger bottleneck than the GPU, and particularly at lower resolutions (e.g. 1080p) the GTX 980M needs plenty of CPU power. If a CPU has to throttle down to lower clock speeds due to excessive heat, overclocking the GPU isn't going to help much. Our stress testing of the P35W v3 seems to have encountered this scenario, and there are times when just running a game on its own can trigger CPU throttling.

Thin + overclocking = questionable

As with any overclocking attempt, the final stable limit will vary even with the same core hardware. We managed a 20% GPU overclock without too much difficulty on the Eurocom P5 Pro (P750ZM), but other P750ZM notebooks might do better or worse than our sample. The Gigabyte P35W v3 with the stock VBIOS also managed to max out the GPU overclock (around 12%), though the benefits aren’t as great thanks to the slower CPU and less robust cooling.

The big question is going to be what overclocking might do to long-term stability and component life. Running the fans in the P750ZM at 100% keeps the GPU running nice and cool even when overclocks, but it could cause the fans to wear out sooner than expected. Having the CPU run in the mid-90s is also a concern, so you might consider buying an extended warranty (even if you don’t plan on overclocking). And while we didn’t have any problems with our P750ZM during testing, we’d be remiss if we didn’t note that we’ve had more than a few high-end gaming notebooks go belly up over the years.

Only NVIDIA and their partners know the exact numbers, but it’s possible NVIDIA has been seeing unacceptably high numbers of mobile GPU failures and locking down overclocking by default would certainly reduce the number of people willing to pursue that route. The true enthusiasts meanwhile can still get what they want by purchasing notebooks that aren’t locked down (e.g. the Clevo P750ZM). Just be careful how far you push the clocks, though, as if you burn out a mobile GPU like the GTX 980M, buying a replacement can cost as much as a desktop GTX Titan X GPU.

There’s a corollary to the overclocking discussion that’s also worth mentioning: underclocking. Sadly, we’ve seen more than one gaming notebook over the years where running stock clocks proved to be difficult if not impossible with certain games, particularly once the notebook is a year old or more. Mostly that has been with mainstream GPUs (e.g. GT 750M and similar), and underclocking by 10-20% will typically fix the problem. We’ve seen others mention this problem as well, and if NVIDIA fully locks down the clock speeds on mobile GPUs it could create unintended consequences for those trying to underclock.

The final tally is that after backlash from the buyers, NVIDIA has decided to not lock out mobile GPU overclocking in their drivers – and true to their word, the latest 347.88 beta drivers allow mobile overclocking again. (The P35W v3 OC testing was done with those drivers.) We might see NVIDIA try to limit overclocking in the future, but hopefully they stick to using a locked VBIOS. That would allow the notebook manufacturers to choose whether or not they want to support GPU overclocking, and that’s probably the best approach as ultimately they’re the ones dealing with RMAs.

And let me end with this warning: I have burned out GPUs in notebooks in the past, even without overclocking, doing stress testing. It’s a terrible feeling to have a notebook suddenly refuse to boot, or crash as soon as the graphics drivers load. While getting a “free” 20% boost to frame rates is definitely nice, replacing/repairing a dead notebook is not. Discretion in this case is not a bad thing, and overclocking a notebook GPU just because you can isn’t without risks.