GPU fan speed slight dip under full load vs load removed quickly

Computer Type: PC/Desktop
System Manufacturer/Model Number: Custom Build
OS: Windows 7 Professional SP1 - x64 [Non-UEFI Boot]
CPU: Ivy Bridge Core i5 3570K (Delidded)
Motherboard: Asus P8Z77-V LE PLUS
Memory: G.Skill "Ares" DDR3 PC3-12800 - 1600MHz (16Gb)
Graphics Card: Asus Dual-RX480-O4G
Sound Card: Creative Sound Blaster Z w/5.1 sound system
Monitor(s) Displays: Asus IPS 23"
Screen Resolution: 16/9
Keyboard: Cooler Master QuickFire XTi
Mouse: Razer Imperator 2012 (4G)
PSU: In Win C 900W Series 80+ Platinum
Case: Thermaltake Chaser A71
Cooling: Custom Water Cooling Loop
Hard Drives: Internal: 500Go Sata 6Gb/s (x2) 500Go Sata 3Gb/s (x2) SSD 60Go Sata 6Gb/s
Browser: IE 11.0.xxx Rtm
Antivirus: MSE
Other Info: "Raid0" with Intel Smart Response Technology (HDD/SSD)

Computer Type: PC/Desktop
System Manufacturer/Model Number: HP Elite 8300 compaq SFF
OS: Windows 7 Pro x64
CPU: i7 3770k 3.5ghz up to 3.9ghz turbo boost 4 core 8 thread CPU
Motherboard: HP Elite 8300 compaq SFF OEM board
Memory: 32GB 4x8GB DDR3 1600mhz CL9 patriot viper gaming ram
Graphics Card: ZOTAC GTX 1650 low profile overclocked GPU
Sound Card: realtek integrated HD audio
Monitor(s) Displays: 23" acer gaming 144hz 1ms monitor
Screen Resolution: 1920x1080 @120hz/144hz
Keyboard: REDRAGON mechanical blue switch
Mouse: ZELOTES wired T-90 mouse
PSU: 430w thermaltake smart
Case: HP Elite 8300 compaq SFF
Cooling: Stock + new thermal paste
Hard Drives: ADATA 128GB SSD ADAtA 256GB SSD x1 Seagate 250GB 7200 RPM drive x1 Seagate 500GB 7200 RPM drive
Internet Speed: 10MB/s (80mbps) download good internet
Browser: IE11 + firefox + Google Chrome randomly switches between
Antivirus: in-use/other
Other Info: Info updated power supply doesnt fit but still works with adapter its just sitting on the desk behind the computer wires going into the case where the old power supply was.