What is the expected portion of the data center business that will be driven by HPC in 2021
 in the second half of this year and going into next year. So we're pleased with the performance on the internal workloads. We see that carrying over to Milan, and sort of the -- the -- let's call it the move from Rome to Milan is -- is -- is not too heavy a lift.
And so we expect that that will continue going into 2021. And in terms of the external facing workloads, we've spent quite a bit of effort sort of building our let's call it sort of the business development engine that sort of let's call it sells along with the cloud vendors, as well as frankly enterprise OEMs. And so our conversation with large enterprises is -- is usually a hybrid conversation. It's -- if you want to buy on-prem, let me tell you what AMD EPYC can do.
If you want to use cloud instances, we have a wide variety of cloud instances across all of the largest cloud vendors. And -- and that's actually progressed very nicely. So I think, overall, that -- that's leading to some of our positive commentary in cloud is that we have seen both progress on internal as well as the external sell with motion.
Joe Moore -- Morgan Stanley -- Analyst
Great. Thank you. And then I wonder in terms of data center GPU, you've talked about some of the emerging applications. Because gaming has been an investment that some of your customers have made, what's the status of that and how -- how big a portion of your data center GPU business do you expect to be driven by cloud gaming in 2021?
Lisa Su -- President and Chief Executive Officer
Sure. So I think the cloud gaming portion of the business was a larger portion of the business in sort of past years for the data center GPU. In 2021, we -- we do have additional cloud gaming engagements that will ramp. But I would say it would be the smaller portion of the business and HPC would become let's call it the larger portion of the business in 2021.
Joe Moore -- Morgan Stanley -- Analyst
Great. Thank you very much.
Lisa Su -- President and Chief Executive Officer
Thanks, Joe.
Operator
Thank you. Our final question today is coming from Timothy Arcuri from UBS. Your line is now live.
Timothy Arcuri -- UBS -- Analyst
Hi. Thanks -- thanks for fitting me in here. So I guess my first question, Lisa, based on your commentary on data center revenues and your splits and you answered the question before about ASPs in Q4. It sounds like server CPU share is running like 12.5% on your $20 million TAM-based that you use.
So you have Milan ramping and you're talking about a lot of visibility on that ramp this year. So I'm sort of wondering if maybe you can give us what your guidance implies or sort of what the next milepost to think of would be in terms of server CPU share as you sort of exit the year and maybe look into next year?
Lisa Su -- President and Chief Executive Officer
Yeah. So Tim, thanks for the question. What -- what I would say is I don't have a new market share target and I think just given all of the -- the variance in the market. But what I will say is we've given you a good view of the business through sort of the percent of -- of revenue it is.
And as I said in the prepared remarks, the -- the -- the data center business was high-teens percentage of annual revenue and it was predominantly -- predominantly server. So the data center GPU was a very small piece of that, and it was predominantly server. As we go into 2021, again, we see significant growth. I would say it's one of the -- the key growth drivers for the company and we'll give you updates as we go along the way in -- in 2021 in -- in terms of how -- how it's growing as -- as a relative size of -- of the business.
Timothy Arcuri -- UBS -- Analyst
OK. Got it. And then just quickly on data center GPU. It looks like it was maybe flattish this year, year over year.
And obviously, it's going to grow this year as Frontier -- Frontier comes in the year. Can you just sort of maybe give us some sense in terms of how much you think it could grow? I mean could it double year over year? I understand it's not big from a dollar point of view, but could it double year over year? M
 in the second half of this year and going into next year. So we're pleased with the performance on the internal workloads. We see that carrying over to Milan, and sort of the -- the -- let's call it the move from Rome to Milan is -- is -- is not too heavy a lift.
And so we expect that that will continue going into 2021. And in terms of the external facing workloads, we've spent quite a bit of effort sort of building our let's call it sort of the business development engine that sort of let's call it sells along with the cloud vendors, as well as frankly enterprise OEMs. And so our conversation with large enterprises is -- is usually a hybrid conversation. It's -- if you want to buy on-prem, let me tell you what AMD EPYC can do.
If you want to use cloud instances, we have a wide variety of cloud instances across all of the largest cloud vendors. And -- and that's actually progressed very nicely. So I think, overall, that -- that's leading to some of our positive commentary in cloud is that we have seen both progress on internal as well as the external sell with motion.
Joe Moore -- Morgan Stanley -- Analyst
Great. Thank you. And then I wonder in terms of data center GPU, you've talked about some of the emerging applications. Because gaming has been an investment that some of your customers have made, what's the status of that and how -- how big a portion of your data center GPU business do you expect to be driven by cloud gaming in 2021?
Lisa Su -- President and Chief Executive Officer
Sure. So I think the cloud gaming portion of the business was a larger portion of the business in sort of past years for the data center GPU. In 2021, we -- we do have additional cloud gaming engagements that will ramp. But I would say it would be the smaller portion of the business and HPC would become let's call it the larger portion of the business in 2021.
Joe Moore -- Morgan Stanley -- Analyst
Great. Thank you very much.
Lisa Su -- President and Chief Executive Officer
Thanks, Joe.
Operator
Thank you. Our final question today is coming from Timothy Arcuri from UBS. Your line is now live.
Timothy Arcuri -- UBS -- Analyst
 Hi. Thanks -- thanks for fitting me in here. So I guess my first question, Lisa, based on your commentary on data center revenues and your splits and you answered the question before about ASPs in Q4. It sounds like server CPU share is running like 12.5% on your $20 million TAM-based that you use.
So you have Milan ramping and you're talking about a lot of visibility on that ramp this year. So I'm sort of wondering if maybe you can give us what your guidance implies or sort of what the next milepost to think of would be in terms of server CPU share as you sort of exit the year and maybe look into next year?
Lisa Su -- President and Chief Executive Officer
Yeah. So Tim, thanks for the question. What -- what I would say is I don't have a new market share target and I think just given all of the -- the variance in the market. But what I will say is we've given you a good view of the business through sort of the percent of -- of revenue it is.
And as I said in the prepared remarks, the -- the -- the data center business was high-teens percentage of annual revenue and it was predominantly -- predominantly server. So the data center GPU was a very small piece of that, and it was predominantly server. As we go into 2021, again, we see significant growth. I would say it's one of the -- the key growth drivers for the company and we'll give you updates as we go along the way in -- in 2021 in -- in terms of how -- how it's growing as -- as a relative size of -- of the business.
Timothy Arcuri -- UBS -- Analyst
OK. Got it. And then just quickly on data center GPU. It looks like it was maybe flattish this year, year over year.
And obviously, it's going to grow this year as Frontier -- Frontier comes in the year. Can you just sort of maybe give us some sense in terms of how much you think it could grow? I mean could it double year over year? I understand it's not big from a dollar point of view, but could it double year over year? M