This is my first post after signing in but I have been active for a while reading review and fix about SP3 before jumping to the 4. Wanted to see if I could actually keep my SP3 or if it was worth it to jump on the 4. I have both machine at the moment but definitely keeping the SP4 for sure. The only issue I have with this unit SP4 is backlight leakage which SP3 didn't have. Scare to exchange it since is running 100% rock solid. Now please read this if you are deciding on getting the M3 version over the i5 because is fan less and what not. I almost jump in the same wagen cause some users here keep recommending the m3 (slow) to the i5. if you want to save $100 but get a machine slower than an i5 SP3 fine by me. I have my SP4 for a week now and the only time the fan went ON was the first day I booted up and was doing a 1 hour update. I have yet to hear the fan or for that matter to get WARM. This thing stay super cool on the regular task I do. online (edge browser), youtube, Netflix, work processing, wordpress and website building, photoshop. etc I Got the i5 4gb 128gb which was gthe same SP3 version I got but the heat and fan noise while browsing or doing simple things would drive me mad. I did all the tweak I could possibly find, using different browser, clean installing win 10, disabling index, lowering max core. Still would get freaking hot. Microcenter have going on right now a special for the i5 sp4 same price has the m3 ($900), so I gave the i5 a shot but was almost ready to return it after hearing all the horror stories here. Now I believe that there's some bad batch of i5 cause I hear people complaining of fan noise, and heat. If this is your case you should return it until u get a good one. Overall the jump from Sp3 to Sp4 is like night and day, everything is much faster and cooler. screen much better, love the pen magnetic attach is super strong. Happy so far, it would have been a perfect machine without the backlight leakage but is not noticeable only in the bootup screen max brightness.