Xiaomi Mi 9 Pro vs. Asus ROG Phone II: A Deep Dive into Flagship Performance and Features

Released within a similar timeframe, the Xiaomi Mi 9 Pro and Asus ROG Phone II represent distinct approaches to the flagship smartphone experience. The Mi 9 Pro aims for a balanced premium experience with a focus on fast charging and wireless capabilities, while the ROG Phone II is unapologetically geared towards mobile gaming, prioritizing sustained performance and battery endurance. This comparison dissects their strengths and weaknesses to determine which device delivers the best value for different user profiles.
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🏆 Quick Verdict

For the average user prioritizing all-around functionality and cutting-edge charging tech, the Xiaomi Mi 9 Pro emerges as the winner. Its 40W wired and 30W wireless charging significantly outperform the ROG Phone II’s 30W wired charging, offering greater convenience. However, gamers will find the ROG Phone II’s optimized thermal design and gaming-centric features more compelling.

PHONES
Phone Names Xiaomi Mi 9 Pro Asus ROG Phone II ZS660KL
Network
2G bandsGSM 850 / 900 / 1800 / 1900GSM 850 / 900 / 1800 / 1900
3G bandsHSDPA 850 / 900 / 1700(AWS) / 1900 / 2100HSDPA 850 / 900 / 1900 / 2100
4G bands1, 2, 3, 4, 5, 7, 8, 12, 17, 41 - China1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 28, 29, 32, 34, 38, 39, 40, 41, 46
SpeedHSPA 42.2/5.76 Mbps, LTE (7CA) Cat20 2000/150 MbpsHSPA 42.2/5.76 Mbps, LTE (5CA) Cat18 (Cat20 Ultimate edition) 1200/150 Mbps
TechnologyGSM / CDMA / HSPA / LTEGSM / HSPA / LTE
 CDMA 800 & TD-SCDMA-
Launch
Announced2019, September. Released 2019, September2019, July 22. Released 2019, September
StatusDiscontinuedDiscontinued
Body
BuildGlass front (Gorilla Glass 6), glass back (Gorilla Glass 5), aluminum frame (7000 series)Glass front (Gorilla Glass 6), glass back (Gorilla Glass 3), aluminum frame
Dimensions157.2 x 74.6 x 8.5 mm (6.19 x 2.94 x 0.33 in)171 x 77.6 x 9.5 mm (6.73 x 3.06 x 0.37 in)
SIMNano-SIM + Nano-SIMNano-SIM + Nano-SIM
Weight196 g (6.91 oz)240 g (8.47 oz)
 -RGB light panel (on the back)
Display
ProtectionCorning Gorilla Glass 6Corning Gorilla Glass 6
Resolution1080 x 2340 pixels, 19.5:9 ratio (~403 ppi density)1080 x 2340 pixels, 19.5:9 ratio (~391 ppi density)
Size6.39 inches, 100.2 cm2 (~85.5% screen-to-body ratio)6.59 inches, 106.6 cm2 (~80.3% screen-to-body ratio)
TypeSuper AMOLED, HDR10AMOLED, 1B colors, 120Hz, HDR10
Platform
CPUOcta-core (1x2.96 GHz Kryo 485 & 3x2.42 GHz Kryo 485 & 4x1.8 GHz Kryo 485)Octa-core (1x2.96 GHz Kryo 485 & 3x2.42 GHz Kryo 485 & 4x1.78 GHz Kryo 485)
ChipsetQualcomm SM8150 Snapdragon 855+ (7 nm)Qualcomm SM8150 Snapdragon 855+ (7 nm)
GPUAdreno 640 (700 MHz)Adreno 640 (700 MHz)
OSAndroid 10, MIUI 11Android 9.0 (Pie), ROG UI
Memory
Card slotNoNo
Internal128GB 8GB RAM, 256GB 8GB RAM, 256GB 12GB RAM, 512GB 12GB RAM128GB 8GB RAM, 256GB 12GB RAM, 512GB 12GB RAM, 1TB 12GB RAM
 UFS 2.1UFS 3.0
Main Camera
Dual-48 MP, f/1.8, 26mm (wide), 1/2.0", 0.8µm, PDAF 13 MP, f/2.4, 11mm (ultrawide)
FeaturesLaser AF, Dual-LED flash, HDR, panoramaLaser AF, LED flash, HDR, panorama
Single-5 MP
Triple48 MP, f/1.8, 27mm (wide), 1/2.0", 0.8µm, PDAF 12 MP, f/2.2, 54mm (telephoto), 1/3.6", 1.0µm, PDAF, 2x optical zoom 16 MP, f/2.2, 13mm (ultrawide), 1/3.0", 1.0µm, PDAF-
Video4K@30/60fps, 1080p@30/120/240fps, 1080p@960fps4K@30/60fps, 1080p@30/60/240fps, 720p@480fps; gyro-EIS (except @240/480fps)
Selfie camera
FeaturesHDRPanorama, HDR
Single20 MP, f/2.0, (wide), 1/3", 0.9µm24MP, f/2.2, 0.9µm
Video1080p@30fps1080p@30fps
Sound
3.5mm jack NoYes
35mm jackNoYes
Loudspeaker YesYes, with DTS:X stereo speakers (2 dedicated amplifiers)
 -24-bit/192kHz audio
Comms
Bluetooth5.0, A2DP, LE, aptX HD5.0, A2DP, LE, aptX HD
Infrared portYes-
NFCYesYes
PositioningGPS (L1+L5), GLONASS (L1), BDS (B1), GALILEO (E1+E5a)GPS (L1+L5), GLONASS, BDS, GALILEO, QZSS
RadioNoFM radio
USBUSB Type-C 2.0, OTGUSB Type-C 3.1, accessory connector, OTG
WLANWi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct, DLNAWi-Fi 802.11 a/b/g/n/ac/ad, dual-band, Wi-Fi Direct
Features
SensorsFingerprint (under display, optical), accelerometer, gyro, proximity, compassFingerprint (under display, optical), accelerometer, gyro, proximity, compass
Battery
Charging40W wired, QC4 30W wireless 10W reverse wireless30W wired 10W reverse wired, QC4
Stand-by-Up to 150 h (3G)
Talk time-Up to 5 h (3G)
TypeLi-Po 4000 mAh, non-removableLi-Po 6000 mAh, non-removable
Misc
ColorsDream White, Titanium BlackMatte Black, Glossy Black
Models-ASUS_I001D, I001DA, I001DE, I001DC, I001DB, I001D, I001DD
PriceAbout 500 EURAbout 1070 EUR
Tests
Battery life- Endurance rating 114h
Camera- Photo / Video
Display- Contrast ratio: Infinite (nominal)
Loudspeaker- -19.5 LUFS (Excellent)
Performance- AnTuTu: 398935 (v7), 483239 (v8) GeekBench: 10923 (v4.4) GFXBench: 40fps (ES 3.1 onscreen)

Xiaomi Mi 9 Pro

  • Significantly faster wired and wireless charging (40W/30W)
  • Reverse wireless charging capability
  • Likely superior camera system (based on brand reputation)

  • Potentially less optimized thermal management for sustained gaming
  • Battery life likely lower than ROG Phone II

Asus ROG Phone II ZS660KL

  • Exceptional battery life (114h endurance rating)
  • Optimized thermal design for sustained gaming performance
  • High display brightness (626 nits)

  • Slower charging speeds (30W wired)
  • No wireless charging
  • Camera likely less advanced than Mi 9 Pro

Display Comparison

Both devices utilize the Snapdragon 855+ chipset, but their display approaches differ. The Asus ROG Phone II boasts a measured peak brightness of 626 nits, providing excellent visibility in bright conditions. While the Mi 9 Pro’s display specs aren’t provided, Xiaomi typically employs high-quality AMOLED panels. The ROG Phone II’s ‘Infinite’ contrast ratio, typical of OLED technology, delivers deep blacks and vibrant colors. The lack of detailed display specs for the Mi 9 Pro makes a direct comparison difficult, but the ROG Phone II’s brightness is a clear advantage for outdoor use.

Camera Comparison

Both phones feature 'Photo / Video' capabilities, but detailed camera specifications are absent. Given the ROG Phone II’s gaming focus, its camera system is likely optimized for general use rather than photographic excellence. The Mi 9 Pro, positioned as a flagship, likely incorporates a more sophisticated camera system with features like OIS and larger sensors. Without specific sensor size or aperture data, it’s difficult to make a definitive judgment, but Xiaomi’s history suggests a stronger emphasis on camera quality in its flagship devices.

Performance

Both the Xiaomi Mi 9 Pro and Asus ROG Phone II are powered by the Qualcomm Snapdragon 855+ (7nm). The CPUs are nearly identical, featuring an octa-core configuration with a 2.96 GHz Kryo 485 prime core, three 2.42 GHz Kryo 485 cores, and four 1.8 GHz (Mi 9 Pro) / 1.78 GHz (ROG Phone II) Kryo 485 cores. The slight difference in the lower core clock speeds is unlikely to be noticeable in real-world usage. However, the ROG Phone II’s design prioritizes thermal management, crucial for maintaining peak performance during extended gaming sessions. While the Mi 9 Pro offers strong performance, the ROG Phone II’s active cooling solutions (not detailed in the provided data, but a key feature) likely provide superior sustained performance under heavy load.

Battery Life

The Asus ROG Phone II boasts an impressive endurance rating of 114 hours, indicating exceptional battery life. The Mi 9 Pro’s battery capacity isn’t specified, but its 40W wired charging and 30W wireless charging capabilities are a significant advantage. The ROG Phone II offers 30W wired charging and 10W reverse wired charging. While the ROG Phone II excels in longevity, the Mi 9 Pro’s faster charging speeds allow for quicker top-ups, making it more convenient for users who frequently need to recharge. The Mi 9 Pro also adds 10W reverse wireless charging, a feature absent on the ROG Phone II.

Buying Guide

Buy the Xiaomi Mi 9 Pro if you need a versatile flagship with incredibly fast charging, both wired and wireless, and appreciate a more refined, everyday smartphone experience. Buy the Asus ROG Phone II ZS660KL if you prioritize sustained gaming performance, long battery life during intense sessions, and are willing to trade some charging convenience for a dedicated gaming experience.

Frequently Asked Questions

❓ Does the ROG Phone II’s cooling system significantly reduce throttling during prolonged gaming sessions?
While the provided data doesn’t detail the ROG Phone II’s cooling system, Asus is renowned for its advanced thermal solutions in ROG devices. These typically include vapor chambers and/or external fan attachments, designed to dissipate heat effectively and maintain peak performance for extended periods, minimizing throttling compared to passively cooled devices.
❓ How much faster is the Mi 9 Pro’s 40W charging compared to the ROG Phone II’s 30W charging in real-world usage?
The Mi 9 Pro’s 40W charging will noticeably reduce charging times. Expect a significantly faster 0-100% charge compared to the ROG Phone II’s 30W charging. While exact times depend on battery capacity (unspecified for the Mi 9 Pro), the 40W standard typically delivers a full charge in under an hour, while 30W may take closer to 1.5-2 hours.
❓ Is the 10W reverse wireless charging on the Mi 9 Pro useful for topping up accessories like earbuds?
Yes, the 10W reverse wireless charging is a convenient feature for wirelessly charging accessories like earbuds or smartwatches. While not as fast as dedicated wireless chargers, it provides a useful emergency charging option when a power outlet isn’t available.