Dell XPS 9550 CPU Multiplier Stuck at 8

Hi,

I recently noticed my new xps 15 9550 is really slow. So I downloaded CPU-Z to take a deeper look. I found the multiplier of CPU is stuck at 8, no matter how much stress I put on the CPU by running stress test like prime64. 

Then I tried to disabled SpeedStep in BIOS and the problem still remains.

Now I have to use ThrottleStop 8.00 to force the multiplier to 26 in order to get get the normal performance. In ThrottleStop I had to uncheck BD PROCHOT option in order to force the multiplier. According to ThrottleStop document, BD PROCHOT stands for Bi-Directional Processor Hot. This allows other items to signal the CPU to tell it that the CPU is hot and that it should throttle even when it isn't. It might be the GPU or the power regulator when it gets too hot or starts putting out too much power that signals the CPU to throttle and conserve power and cool down the overall system temperature.

Is this a known issue? Is there a good solution instead of relying on ThrottleStop?

=====Attached CPU-Z report.

Processor 1 ID = 0
Number of cores 4 (max 8)
Number of threads 8 (max 16)
Name Intel Core i7 6700HQ
Codename Skylake
Specification Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
Package (platform ID) Socket 1440 FCBGA (0x5)
CPUID 6.E.3
Extended CPUID 6.5E
Core Stepping R0
Technology 14 nm
TDP Limit 45.0 Watts
Tjmax 100.0 °C
Core Speed 798.0 MHz
Multiplier x Bus Speed 8.0 x 99.8 MHz
Stock frequency 2600 MHz
Instructions sets MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, EM64T, VT-x, AES, AVX, AVX2, FMA3, TSX
L1 Data cache 4 x 32 KBytes, 8-way set associative, 64-byte line size
L1 Instruction cache 4 x 32 KBytes, 8-way set associative, 64-byte line size
L2 cache 4 x 256 KBytes, 4-way set associative, 64-byte line size
L3 cache 6 MBytes, 12-way set associative, 64-byte line size
FID/VID Control yes

Turbo Mode supported, enabled
Max non-turbo ratio 26x
Max turbo ratio 35x
Max efficiency ratio 8x
O/C bins none
Ratio 1 core 35x
Ratio 2 cores 33x
Ratio 3 cores 32x
Ratio 4 cores 31x
TSC 2592.0 MHz
TSC_24 24.0 MHz
APERF 798.2 MHz
MPERF 2594.0 MHz
IA Voltage Mode PCU adaptive
IA Voltage Offset 0 mV
GT Voltage Mode PCU adaptive
GT Voltage Offset 0 mV
LLC/Ring Voltage Mode PCU adaptive
LLC/Ring Voltage Offset 0 mV
Agent Voltage Mode PCU adaptive
Agent Voltage Offset 0 mV

Temperature 0 41°C (105°F) [0x3B] (Core #0)
Temperature 1 43°C (109°F) [0x39] (Package)
Power 0 4.12 W (Package)
Power 1 1.90 W (IA Cores)
Power 2 0.06 W (GT)
Power 3 2.15 W (Uncore)
Power 4 1.28 W (DRAM)
Voltage 0 0.80 Volts (VID)
Voltage 1 +0.00 Volts (IA Offset)
Voltage 2 +0.00 Volts (GT Offset)
Voltage 3 +0.00 Volts (LLC/Ring Offset)
Voltage 4 +0.00 Volts (System Agent Offset)