diff --git a/Cicm.Database/Models/ResolutionsByGpu.cs b/Cicm.Database/Models/ResolutionsByGpu.cs
index 44a7d41a..7f9dbce5 100644
--- a/Cicm.Database/Models/ResolutionsByGpu.cs
+++ b/Cicm.Database/Models/ResolutionsByGpu.cs
@@ -29,12 +29,15 @@
 *******************************************************************************/
 
 using System.ComponentModel;
+using Microsoft.AspNetCore.Mvc;
 
 namespace Cicm.Database.Models
 {
     public class ResolutionsByGpu : BaseModel<long>
     {
-        public int GpuId        { get; set; }
+        [Remote("VerifyUnique", "ResolutionsByGpu", "Admin", AdditionalFields = nameof(ResolutionId))]
+        public int GpuId { get; set; }
+        [Remote("VerifyUnique", "ResolutionsByGpu", "Admin", AdditionalFields = nameof(GpuId))]
         public int ResolutionId { get; set; }
 
         [DisplayName("GPU")]
diff --git a/cicm_web/Areas/Admin/Controllers/ResolutionsByGpuController.cs b/cicm_web/Areas/Admin/Controllers/ResolutionsByGpuController.cs
index 8b2811a7..13e808e6 100644
--- a/cicm_web/Areas/Admin/Controllers/ResolutionsByGpuController.cs
+++ b/cicm_web/Areas/Admin/Controllers/ResolutionsByGpuController.cs
@@ -169,5 +169,14 @@ namespace cicm_web.Areas.Admin.Controllers
         {
             return _context.ResolutionsByGpu.Any(e => e.Id == id);
         }
+
+        [AcceptVerbs("Get", "Post")]
+        public async Task<IActionResult> VerifyUnique(int gpuId, int resolutionId)
+        {
+            return await _context.ResolutionsByGpu.FirstOrDefaultAsync(i => i.GpuId        == gpuId &&
+                                                                            i.ResolutionId == resolutionId) is null
+                       ? Json(true)
+                       : Json("The selected GPU already has the selected resolution.");
+        }
     }
 }
\ No newline at end of file
diff --git a/cicm_web/Areas/Admin/Views/ResolutionsByGpu/Create.cshtml b/cicm_web/Areas/Admin/Views/ResolutionsByGpu/Create.cshtml
index cbbd772d..a129da9b 100644
--- a/cicm_web/Areas/Admin/Views/ResolutionsByGpu/Create.cshtml
+++ b/cicm_web/Areas/Admin/Views/ResolutionsByGpu/Create.cshtml
@@ -22,6 +22,9 @@
                         class="form-control"
                         asp-items="ViewBag.GpuId">
                 </select>
+                <span asp-validation-for="GpuId"
+                      class="text-danger">
+                </span>
             </div>
             <div class="form-group">
                 <label asp-for="Resolution"
@@ -31,6 +34,9 @@
                         class="form-control"
                         asp-items="ViewBag.ResolutionId">
                 </select>
+                <span asp-validation-for="ResolutionId"
+                      class="text-danger">
+                </span>
             </div>
             <div class="form-group">
                 <input class="btn btn-primary"
diff --git a/cicm_web/cicm_web.csproj b/cicm_web/cicm_web.csproj
index 508aadcc..62db468e 100644
--- a/cicm_web/cicm_web.csproj
+++ b/cicm_web/cicm_web.csproj
@@ -2,7 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
   <PropertyGroup>
     <TargetFramework>netcoreapp2.2</TargetFramework>
-    <Version>3.0.99.503</Version>
+    <Version>3.0.99.504</Version>
     <Company>Canary Islands Computer Museum</Company>
     <Copyright>Copyright © 2003-2018 Natalia Portillo</Copyright>
     <Product>Canary Islands Computer Museum Website</Product>