XFX RX 6600 XT MERC 308

XFX RX 6600 XT MERC 308: Introduction

Hello and welcome to another review here at Overclockers Club. Today we will be taking a detailed look at the XFX RX 6600 XT MERC 308, which is backed by AMD's RDNA2 architecture and a formidable opponent to NVIDIA. It seems like déjà vu with another attempt from AMD to secure a win for the team. We are getting closer to the year mark from which AMD released the long-anticipated RDNA2 architecture, the successor to AMD's latest major GPU overhaul. The company's second attempt in recent years trying to take the performance crown back away from NVIDIA, a company that has held the title for far too long now.

Now that both contenders have released several graphics cards packaged with the newest innovations, it is still unclear who the victor is. Neither ultra-high-end video card outperforms the other in everything and both cost the equivalent of selling multiple organs right now! But enough about that of which we cannot afford. It is no secret AMD has been the underdog for several years and with the RDNA architecture used in the RX 5700 XT only reaching mid-tier status among the competition, it didn't help sell the idea that AMD is a real threat to upset the trend we have been accustomed to as of late. That changed with the RX 6000 series and healthy competition has emerged driving innovations in technologies once again. AMD has time and time again made the companies intentions clear and to give gamers compelling choice not to purchase any NVIDIA graphic card with a GPU at every price point to match.

I made the mistake of calling NVIDIA RTX 3060 a budget graphics card in my recent review as $300+ (USD) is indeed a bit on the high side for those casual gamers. But my decision to call it as such is simply because we are reaching the bottom of the barrel of this generation, which leaves little to be worthwhile to manufacture in terms of profitability. Yes, an even lower tier may present itself, however not without major sacrifice to performance. The RX 6600 XT takes its place as this generation's "budget" video card and is priced between NVIDIA's RTX 3060 and RTX 3060 Ti as entry-level mid-range GPU. Due to high demand, supply chain issues, and inflation, I do not think anything will return the pricing structure of 2019. At least not for this generation.

By strategically placing it between the gap left by NVIDIA, AMD hopes to appeal to those who want the middle ground. It is also being presented as a direct replacement for the last generation's RX 5700 (Non-XT), now with ray-tracing support. Ray-tracing is something NVIDIA has been pushing since the last generation of RTX-enabled GPUs. With both DirectX 12U and Vulkan API supporting this new way to experience games, it almost becomes necessary for AMD to have support for it as well. However because this graphics card is mainly targeting 1920 x 1080 resolution for gamers, chances are any sort of ray-tracing enhancements will be forgone by many in favor of higher sustained frame rates. More on that topic later.

At the core of every RX 6600 XT is AMD's 2nd generation of RDNA architecture (RDNA2) as briefly discussed before. The NAVI-21 Silicon is the backbone of the RX 6800, RX 6800 XT, and RX 6900 XT. While the RX 6700 XT has a NAVI-22 all to itself, which is yet another chop to the die. The RX 6600 XT as you may have guessed is NAVI-23 silicon with 36 Compute Units (CU) over a 128-bit memory bus. With it comes 2048 Stream Processors and 8 GB of GDDR6 VRAM. It is a little behind the RX 6700 XT, but still a spectacular setup for those who have been waiting to upgrade without breaking the bank.

XFX's R&D team continues to build upon the MERC lineup and with that comes performance we can expect. So let's get right into the review and see what XFX has to offer compared to the competition. In this review, I benchmarked the GPU on multiple systems, games, resolutions, and ray-tracing. We will be going over temperatures and power consumption, and overclocking as well. This is another one of those monstrous reviews with lots of topics, so let's get started!

XFX RX 6600 XT MERC 308: Closer Look

What do you have here? Another box yes! As always I point out that I do not care about any boxes unless it holds some sort of collectors value. How the graphics card is package should be the most important topic. As seen below it is well preserved with an ample amount of foam padding to make the trip. While on the topic of boxes, a learned a fun fact that maybe I should have already known. You know because I'm the one reviewing said products. In any case, the numbers used are not as arbitrary as I once thought. The first number indicates the number of fans, second and third is the size. This since this RX 6600 XT has three 80mm fans, it carries the number 308. The 6700 XT, 6800, and above have three fans, but one is 100mm with two 90mm. Hence the name 319. Information you did not need, but interesting to understand why it is written this way nonetheless.

Now it is out of the box we can get a closer look and talk about what makes this RX 6600 XT stand out among the many partner cards on the market. The MERC 308 is on the larger side for what I would consider necessary for an operational thermal load of 145 watts. Coming in at 10.79 inches in length, it is longer than any ATX motherboard. However, I prefer better thermal cooling if at all possible, so the size becomes justifiable. This is just personal preference of course. Pair the 2.3 slot cooler with quieter fans and you have struck gold!

The MERC series is recognizable from far away with a black cooler shroud and silver accent rings around each 80mm 9-bladed fan. Flip the card around and the rear has a passthrough exhaust allowing more ways for the heat to be pushed away. The aluminum backplate also provides extra stability and rigidity throughout the card. No snag at all, but remember to properly secure the card to the chassis, otherwise the weight load will be placed upon the PCIe slot. If you were to disassemble it, at the base is nickel plated cold plate made out of copper connected to four 6mm heat pipes. This heat sink also makes contact with the 6+2 phase VRM. This card is using an IR35217 Phase Digital Controller from Infineon Technologies. XFX has opted to use 6x NCP302155 from ON Semiconductor. These are 55 amp drivers. Do a little backhand math and at a GPU peak voltage of 1.15v, this card can deliver 330 amps or 379 watts. It is a nice buffer considering that the vBIOS limit is currently set to 145 watts.

Just a quick rehash here. The MERC 308 is powered by a single 8-pin PEG connector. This is more than enough considering the GPU voltage limit. the vBIOS is also limited to 145 watts. However, the good is news is that the ability to exceed the specifications of the cable and connector is not possible and does leave room for future XFX BIOS updates that may allow for a higher power target. Speaking of the power limit, XFX has included a toggle vBIOS switch as with most of its models. For many partner cards, the dual vBIOS allows the user to pick between the standard/OC or a silent mode via the toggle. For the XFX RX 6600 XT, it has no secondary preset. Both vBIOS are identical for the time being. Why this might be is a bit of mystery, however, I think it has to do with some AMD driver restrictions, plus the GPU frequency can only go so high, making a higher wattage vBIOS unnecessary for this series.

XFX follows suit with the RX 6700 XT reference design, which has made one significant change by removing the USB-C 10Gbps connector found on the 6800/6900 series. While VR headsets could make use of a USB-C port, I think the adoption rate has been very slow, thus making more sense as a company to reduce costs slightly by removing the port completely. Remember this is a 10Gbps interface, not 20 or 40Gbps that is necessary for most monitors. Not a major loss in my opinion. While no "reference" RX 6600 XT exists directly from AMD, it does work with board partners to provide reference design layouts and suggestive use. By following a standard design format for the I/O section, XFX has the same configuration seen on the RX 6700 XT: three 1.4b DisplayPorts and a single HDMI 2.1. For the intended market, this is acceptable.

With the MERC 308 plugged in and powered on you can see it isn't a showstopper and limited lighting besides the Radeon logo. It has no other lighting effects. If you are hurting for that RGB goodness, XFX isn't a good option. I do want to point out that the ridged backplate helps the card from slouching. It is as straight as an arrow. Mounting it vertically with a PCIe raiser isn't worth the hassle to set up unless you already have it installed previously. You do not gain much from a visual standpoint if any at all.

Alright, I think that covers everything, now it's time to get to the benchmarks and see how well it overclocks while we are at it.