Puget Systems print logo
Read this article at https://www.pugetsystems.com/guides/979
Article Thumbnail

X299 vs X99: What is the Difference?

Written on July 11, 2017 by Matt Bach


Alongside the new Skylake-X (Core i7-78xx & i9-79xx) and Kaby Lake-X (Core i7-77xx & i5-76xx) CPUs, Intel has also released the accompanying X299 Chipset. These days, new chipsets are rarely very exciting as more and more functionality is moved onto the CPU, but we wanted to cover what differences there are between X299 and the previous generation X99 chipset. 

If you are curious how the new Skylake-X and Kaby Lake-X CPUs themselves perform, we currently have articles looking at how they compare to the Intel Broadwell-E and Skylake CPUs as well as the AMD Ryzen 7 CPUs for the following applications:

X299 vs X99 Chipset Specifications

There are a number of changes between X299 and X99 and we marked the major differences in the chart below with red. Note that this chart doesn't include all the features available in each chipset, but rather the key points we feel are important. If you wish to see the full set of differences between X299 and X99, Intel.com has a comparison chart you can view.

X299 X99
Processor Support Skylake-X (Core i7-78xx & i9-79xx)
Kaby Lake-X (Core i7-77xx & i5-76xx)
Haswell-E (Core i7-59xx/58xx)
Broadwell-E (Core i7-69xx/68xx)
Socket LGA-2066 LGA-2011 v3
DRAM Support DDR4 DDR4
Mem/DIMMs Per Channel 4/1 4/1
DMI Version 3.0 3.0
Intel Rapid Storage Technology (RST) Yes Yes
Intel RST for PCI-E Storage Yes No
Intel Smart Response Technology (SRT) Yes Yes
Intel Optane Technology Yes No
USB Total (USB 3.0) 14(10) 14(6)
Max SATA 6Gb/s 8 10
Max Additional PCI-E lanes* 24x PCI-E 3.0 8x PCI-E 2.0
CPU Overclocking Yes Yes

*In addition to the 16-44 PCI-E 3.0 lanes from the CPU

Starting from the top, X299 supports the new LGA-2066 socket necessary for the new CPUs, but it has not seen much of a change from a RAM compatibility perspective. Since the memory controller was moved onto the CPU a number of years ago, things like the supported RAM frequency depends on the capabilities of the CPU rather than the chipst. Because of this, the X299 chipset still supports the same 4 channels of memory with one DIMM per channel resulting in most X299 motherboards allowing either four or eight sticks of DDR4 RAM.

The first major addition to the X299 chipset is the support for Intel RST for PCI-E storage devices rather than just SATA storage devices. X299 also adds support for Optane technology which has great potential, but has not really taken off quite yet.

Moving on to connectivity, X299 supports the same total number of USB ports although the number of USB 3.0 has gone up from 6 to 10. Oddly, the number of SATA 6Gb/s ports has been reduced from 10 to 8. It is extremely rare for more than even 4 SATA drives to be used in a system without a 3rd party RAID controller, however, so this reduction really isn't that big of a deal for the vast majority of users.

The biggest change in X299 from a feature standpoint is the number and speed of PCI-E lanes available through the chipset. Where X99 only had 8 PCI-E 2.0 lanes, X299 now has 24 PCI-E 3.0 lanes. This is a massive increase and should make it much easier to use devices like M.2 storage drives or even Thunderbolt without having to worry about how you are going to divide up a small number of PCI-E lanes.


Overall, most of the changes in X299 are quite minor. The extra USB 3.0 ports are nice and while the support for Intel Optane has the potential to be significant, the current implementation is fairly underwhelming for most users.

The most exciting change is the inclusion of 24 PCI-E 3.0 lanes - up from just 8 PCI-E 2.0 lanes on X99. This should greatly help the transition from the somewhat dated SATA 6Gb/s technology to the much higher performance M.2 specification. Since each high speed M.2 drive requires four dedicated PCI-E 3.0 lanes, the inclusion of 24 PCI-E 3.0 lanes is terrific. In fact, a number of ATX X299 boards already on the market include support for up to three full speed M.2 drives. Given that current M.2 drives can run at up to 3.5GB/s for only a ~20% price increase over a high quality SATA drive, we see this as the largest single benefit to X299 for end users.

However, as is often the case, the main reason to use X299 is simply to be able to use the new Skylake-X and Kaby Lake-X CPUs. These CPUs are not supported by the previous generation X99 chipset, so if you want to use these newer CPUs, X299 is really your only option.

Tags: Skylake-X, Kaby Lake-X, X299, X99
Niko Nikolov

You are forgeting something important for x99.It will work with the xeon e5 2600 line and ecc memory.The lga 2066 will support only i7/i9 cpus and no xeons >no ecc(if im not mistaking).So by todays date,if people ¨¨need¨¨ ecc and xeons,than maybe cheap amazon/ebay x99 ofers shoud look appealing?

Posted on 2017-07-13 09:09:26

In these kinds of "vs" articles, we typically try to stick to the official specifications put forth by Intel since anything else can vary by board manufacturer and even by BIOS revision. X99 will indeed work with Xeon E5 CPUs, but I don't believe that is an official part of the platform that Intel technically supports - it is just a nice little bonus. Same thing with Registered memory: it works, but Intel and even most motherboard manufactures do not officially support it. There are some X99 boards that do officially support it (like the Asus X99-E WS 10G) but even on those they say you have to use a Xeon CPU.

X299 (LGA 2066) actually can support Registered memory as well and many of the Gigabyte boards (like this one https://www.gigabyte.com/Mo... ) even list it as officially supported with the existing Core CPUs. They specifically say that ECC doesn't work, but that isn't a surprise given we only have Skylake-X CPUs so far. The new Xeon CPUs haven't launched yet and as far as I know Intel hasn't given a public date as to when they will be available. Whether X299 will work with Xeon CPUs like X99 does will have to wait until they launch.

Posted on 2017-07-13 18:26:28
Niko Nikolov

Doubt that new xeons will work with x299(lga 2066) simply because on intels ark page it shows that all new xeons(gold/platinium) will be lga 3647.So physically bigger than the lga 2066 soket.I really hate how they are separating tech again.You will need a big server motherboard if you want a new xeon and those are so poor on features.Maybe that is the reason we are seing i9 with up to 18cores.If you want a workstation with a cheaper board,than pay premium for a i9...
I supose this is to help them with the fight of those xeons es models.

Posted on 2017-07-14 09:36:19

They are forcing a product segmentation between workstation and consumer motherboards, true. It is bizarre seeing as their competitor has released TR4 motherboards support ECC and non-ECC memory. However in terms of size the Asus C422 WS motherboard is in most cases identical to the Asus X299 WS motherboard. Both ATX. Layout and most of the feature set identical. Just Xeon-W and ECC support from the C422 chipset. It looks like a decent board imo.

Posted on 2018-01-29 13:25:30

Do you think the 7740X would be a good CPU for Lightroom usage? That's the impression I got from this statement...

"The Core i7-7740X appeals to users who want the fastest out-of-the-box single thread x86 processor on the market today. This means financial traders, gamers, and professionals working with serial code bases..." -- Anandtech


Posted on 2017-07-29 05:44:53

We actually have a Lightroom article looking at all the new processors as well as AMD Ryzen: https://www.pugetsystems.co... .

The 7740X is actually the fastest CPU available today for everything we have tested outside of importing and exporting images. Those tasks can take advantage of higher core counts so even the i7 7800X (which is only $50 more) is significantly faster. For everything else like generating previews, creating HDR/panorama images, converting to DNG, scrolling through images, etc., the i7 7740X is currently the king.

Posted on 2017-08-04 16:08:17

I'm curious, why would X99 support only one PCI-E 3.0x4 M.2 drive if there are 28 or 40 lanes straight to the CPU? Seems like an arbitrary limitation.

Posted on 2017-08-09 16:40:13

I know Intel lists a "Max PCIe Storage" on their consumer chipsets like Z270, but I am not sure if they list anything like that on X99 or X299. I wasn't 100% sure, but I double checked the official specs on the Intel page I don't see anything listed. It may have been listed before, but if so they must have removed it. Either way, you totally can do more than one M.2 drive on X99. On the consumer chipsets (like Z270), I believe the offical number of supported PCIe storage devices has to do with the number of PCIe 3.0 lanes available through the chipset. Intel likely estimates the number of lanes that are needed for things like SATA and USB then whatever is left over they divide by 4 and say that is how many M.2 (or other PCIe) storage drives you can use.

From my understanding, Intel likes to think of the PCIe lanes on the CPU as being reserved for things like video cards, sound cards, and other add-on cards so storage they generally intend to go through the chipset rather than the CPU. There is absolutely nothing preventing motherboard manufacturers from using the CPU lanes for that, however, which is why on X99 (where the chipset doesn't support PCIe 3.0 at all) you can still get motherboards that let you use a PCIe 3.0 x4 M.2 drive without any problems.

Honestly, that spec is a really odd one that doesn't really seem to mean much in the real world. As long as you have enough free PCIe lanes of the right speed and the motherboard supports it, you should be able to use as many PCIe storage drives as you want without any issues.

Posted on 2017-08-09 19:44:05
Leslie Standifer

X99 supports 28 and 40 pcie 3.0 lanes you can put whatever you want in them. I put 1gpu and 3x pci ssds. The point of pcie 3.0 ssds are they bypass the DMI Link which can bottleneck them pcie 2.0 goes through the DMI so not sure why you would indicate Intel intends the storage go through the controller

Posted on 2017-08-11 17:31:35

DMI info is wrong.

Posted on 2017-08-11 09:13:30
Yordan Getev

excuse my incompetence here, but when one put multiple Nvme M.2 SSDs on new x299 chipset this means that they are handicapped by 1x4 PCI DMI link?

Posted on 2017-08-14 13:25:17
Laureano Javier Alfaro

"The most exciting change is the inclusion of 24 PCI-E 3.0 lanes - up from just 8 PCI-E 2.0 lanes on X99. "...sorry for the noob question I'm going to make, but does this change if using a Xeon?...this will enable the full pcie lanes potential?like is noticeable I'm a bit confuse about the whole pcie lanes thing, thanxs in advance!

Posted on 2018-08-10 06:48:30