AMD Athlon X2 7850 Black Edition CPU

Athlon X2 7850 Black Edition

• Clock Frequency: 2.8GHz, 200x14
  
• L1 Cache: 64KB data and 64KB instruction per core (256KB in total)
  
• L2 Cache: 512KB exclusive data cache per core (1MB in total)
  
• L3 Cache: 2MB shared (exclusive) data cache
  
• Fabrication Process: 65nm SOI (silicon on insulator)
  
• Socket: AM2+
  
• Memory support: DDR2 1,066MHz
  
• Current Core Stepping: B3
  
• Thermal Design Power (TDP): 89W
  
• Voltage Range: 1.2-1.25 Volts
  
• Transistors: ~450 million
  
• Die Size: 285mm²

The benefit of having the same 2MB L3 cache assigned to fewer cores (than the K10 triple and quad cores) means that there's respectively more space for each to use since the L1 and L2 caches are exclusive to L3, unlike Intel CPUs. Moreover, there is less chance of potential conflicts with only two cores trying to concurrently access it. At least, that's the theory anyway. Compared to Intel's Core 2 Duo which uses a large L2 cache that runs at the CPU frequency instead, the L3 cache is accessed two to three times slower and adds an extra layer of data snooping.

Before Kuma's introduction late last year, the only desktop part that included L3 cache that had two cores or less was Intel's Extreme Edition Galatin core (130nm) based on a single cored Pentium 4 with HyperThreading. This was because it was essentially a Xeon part converted for desktop use and gave it a five percent or less performance advantage. Comparing Intel Netburst to AMD's K8/K10 architecture is like night and day though, so the L3 cache use could yield potentially different impressive results.

Compared to the 45nm Wolfdale core which has ~410 million transistors on a 107mm² die, it's significantly larger in size but only slightly larger in transistor count. However, the Kuma does include a memory controller and approximately 1.5MB extra cache than the Wolfdale. The Kuma is significantly bigger than Intel's older 65nm Conroe though, which has just 291 million transistors with a die size of 143mm² - making the AMD chip nearly twice the size with 80 percent more transistors.

Test Setup

Supplemental Hardware

Graphics Cards: Zotac GeForce GTX 280
Motherboards: Biostar 790GX A2+ (AMD 790GX/SB750) and Asus P5Q Deluxe (Intel P45/ICH10R)
Hard Drive: Seagate Barracuda 7200.9 160GB SATA II
Power Supply: PC Power and Cooling Silencer 750W
Memory: Corsair Dominator XMS2-8500 5-5-5-15, G.Skill Pi-series F3-12800Cl7D-4GBPI, Qimonda PC3-8500U-7-XX-A0
Drivers: Nvidia GeForce 178.13, Intel inf 8.6.1.1001 and 9.1.0.1007
Operating System: Windows Vista Home Premium x64 SP1

Many thanks to Novatech for supplying us with the Intel Pentium Dual Core E5200 CPU used for this review.

CPU Price List

• AMD Athlon X2 7850 Black Edition (2.8GHz, 95W, 1MB total dedicated L2 cache, 2MB L3 cache, 3.6GHz HTT, socket AM2+)
  £61.82 (inc. VAT) | $74.00 (ex. Tax)
  
• AMD Athlon X2 7750 Black Edition (2.7GHz, 95W, 1MB total dedicated L2 cache, 2MB L3 cache, 3.6GHz HTT, socket AM2+)
  £49.99 (inc. VAT) | $58.99 (ex. Tax)
  
• Athlon X2 6000+ (3.1GHz, 89W, 1MB total dedicated L2 cache, 2.2GHz HTT, socket AM2)
  around £68 (inc. VAT) | around $82 (ex. Tax)
  
• Athlon X2 5400
  (2.8GHz, 65W, 2MB total dedicated L2 cache, 2,000MHz HyperTransport bus, socket AM2)
  £54.05 (inc. VAT) | $55.50 (ex. Tax)
  
• Intel Pentium Dual Core CPU E5200 (2MB L2 cache, 2.5GHz, 65W, 800MHz Front Side Bus, 45nm)
  £59.79 (inc. VAT) at Novatech