Intel Core i7-8700K vs. i7-9700K: Used Market Matchup
If you are sitting on an LGA 1151 motherboard, choosing between an i7-8700K and i7-9700K comes down to used pricing versus the trade-off of raw cores against thread count.
The Short Answer for Used Upgrades
If you already own an LGA 1151 (300-series) motherboard and need a cheap drop-in upgrade, the Core i7-9700K is the better gaming chip thanks to its eight physical cores and higher single-core boost clock. However, you should not pay more than a $15 to $20 premium over the Core i7-8700K on the used market. If you are building a system from scratch, buy neither—modern budget chips like the Intel Core i5-12400F or AMD Ryzen 5 5600 wipe the floor with both on power efficiency and single-thread speed while giving you a modern platform.
- Buy the i7-9700K if: You play esports titles or CPU-heavy games, find one under $100 used, and already own a decent Z370 or Z390 motherboard.
- Buy the i7-8700K if: You find a rock-bottom deal under $75, or you run mixed workloads that scale better across 12 threads than 8 pure cores.
- Skip both if: You do not already own a compatible motherboard and DDR4 memory kit. Modern budget platforms offer far better value.
Core Architectural Differences: 6C/12T vs. 8C/8T
The transition from the 8th Gen Coffee Lake to 9th Gen Coffee Lake Refresh marked a weird moment in Intel's history. Facing stiff pressure from AMD's first- and second-generation Ryzen processors, Intel overhauled its desktop hierarchy.
The Core i7-8700K arrived with six physical cores and Hyper-Threading enabled, giving you 12 logical threads. When Intel launched the Core i7-9700K, it stripped Hyper-Threading away from the i7 tier to reserve it exclusively for the pricier Core i9-9900K. To compensate, Intel gave the 9700K eight physical cores. Physical cores beat virtual threads in almost every gaming scenario, but stripping Hyper-Threading meant the 9700K had four fewer simultaneous execution threads than its predecessor.
Intel also switched the thermal interface material (TIM). The 8700K famously used standard thermal paste under the integrated heat spreader (IHS), leading to spicy temperatures unless you delidded the chip. The 9700K brought back a soldered thermal interface (STIM), yielding better heat transfer straight out of the box.
| Feature | Core i7-8700K | Core i7-9700K |
|---|---|---|
| Cores / Threads | 6 / 12 | 8 / 8 |
| Base Clock | 3.7 GHz | 3.6 GHz |
| Max Boost Clock | 4.7 GHz | 4.9 GHz |
| L3 Cache | 12 MB | 12 MB |
| Thermal Interface | Thermal Paste (TIM) | Solder (STIM) |
| TDP | 95W | 95W |
| Socket Support | LGA 1151 (300-series) | LGA 1151 (300-series) |
| Integrated Graphics | UHD Graphics 630 | UHD Graphics 630 |
Gaming Performance Comparison
In standard 1080p gaming, the Core i7-9700K consistently leads the Core i7-8700K by roughly 8% to 15%, depending on how heavily the game leans on clock speed and physical cores. Titles that hammer a single core benefit directly from the 9700K's higher out-of-the-box boost of 4.9 GHz versus the 8700K's 4.7 GHz.
Modern game engines are hungry for physical cores. In titles like Cyberpunk 2077 or open-world shooters, eight full cores provide smoother frame delivery and fewer micro-stutters than a 6-core/12-thread configuration running at a lower frequency. However, the 9700K will occasionally run at near-100% total CPU utilization in modern background-heavy environments because it lacks the extra thread buffer. If you stream using CPU encoding (x264) while gaming, the 8700K's 12 threads can occasionally hold a steadier frame pacing than the pegged 8-thread 9700K, though you should be using your graphics card's NVENC or AMF encoder anyway.
Productivity and Daily Workloads
In synthetic benchmarks and production apps like Blender, Cinebench, and HandBrake, the two processors trade blows surprisingly closely. The 9700K's eight physical cores provide better raw IPC throughput, but the 8700K's Hyper-Threading keeps it competitive in heavy multi-pass encoding.
In Cinebench multi-core runs, the 9700K edges out the 8700K by about 10% on average. For single-core production tasks, such as raster manipulation in Adobe Photoshop or basic audio editing, the 9700K is roughly 7% faster due to its clock speed advantage. For everyday general computing, web browsing, and office workloads, the two feel identical.
Power Consumption and Thermals
Both chips carry a rated 95W TDP, but real-world numbers tell a different story once Turbo Boost kicks in under heavy AVX workloads. The 9700K pulls slightly more power at full tilt—often hovering between 130W and 160W under sustained multi-threaded loads, compared to roughly 120W to 140W for the 8700K.
Despite drawing slightly more power, the i7-9700K is often easier to cool with a mid-range tower cooler because of its soldered IHS. The i7-8700K runs hot due to Intel's paste application beneath the heat spreader. If you plan to overclock the 8700K past 4.8 GHz, expect to need a 240mm liquid cooler or a hefty dual-tower air cooler like a Thermalright Peerless Assassin 120.
Compatibility: Motherboards and Chipsets
Both CPUs drop into the LGA 1151 socket, but pay close attention to chipset revisions. They require an Intel 300-series chipset (such as Z370, Z390, B360, B365, or H310). They are mechanically incompatible with older 100- and 200-series motherboards (Z170, Z270), despite sharing the LGA 1151 pin count.
If you have an older Z370 motherboard, verify your BIOS version before dropping in an i7-9700K. The 8700K booted natively on early Z370 boards, whereas the 9700K requires a BIOS update to recognize the 9th Gen microcode.
Buying New Instead: The Modern Budget Reality
Do not buy either of these processors if you do not already own a 300-series motherboard. A brand-new Intel Core i5-12400F or AMD Ryzen 5 5600 sells brand new for under $110, uses substantially less power, supports PCIe 4.0, and delivers 25% to 35% better single-thread performance than an i7-9700K.
When you add the cost of a used Z390 board to the cost of a used 9700K, you quickly approach $180 to $200. For that same cash, you can buy a brand-new modern processor paired with a budget B660 or B550 motherboard, securing an upgrade path and modern platform features like high-speed M.2 NVMe storage without relying on aging silicon.
FAQ
Can an i7-8700K or i7-9700K run Windows 11 officially?
The Core i7-8700K and Core i7-9700K both officially support Windows 11. They have built-in TPM 2.0 (Intel Platform Trust Technology, or PTT) within the motherboard BIOS and meet Microsoft's processor family requirements without requiring bypasses or registry hacks.
Can I upgrade from an i7-8700K to an i7-9700K on the same motherboard?
Yes. Both CPUs use the LGA 1151 socket on 300-series motherboards. If you are on a Z370 or B360 board, ensure you flash your motherboard to a 9th Gen-compatible BIOS revision before swapping out the 8700K.
Is upgrading from an 8700K to a 9700K worth the cost?
We would skip it. Spending $80 to $100 for a 10% to 12% boost in gaming frame rates is a poor return on investment. If you are currently hitting CPU bottlenecks on an 8700K, your money is far better spent saving toward a full motherboard and platform replacement.